Glossary

This article is a list of definitions that are used in the Daybreak project. Both Covenant and human terms are featured. Most of the Covenant terms are English translations of the original Covenant words unless otherwise noted.

A

 * Actua: Translated classical Covenant term for normal space or realspace; the physical universe.
 * Accretionite: A sedimentary rock formed from accumulated meteorites and space dust.
 * Aether: Common Covenant name for wavespace, the layers of slipspace used for faster-than-light communication
 * Achkhun raahu: translated as "The Broad Path"; a school of Covenant faith which emphasizes the spiritual commonality of all sapient species in their potential for divinity. Popular especially among the Unggoy, and most prominently championed by the Deacon Ilyil in the post-war years. Often used as justification by social reform movements.
 * Agora: The most common type of information network used by Covenant citizens; usually exclusive to city, station or world. Most Covenant civilian networks were also top-down in nature rather than interactive, with interactive networks usually being exclusive to guilds, governmental organizations or military units.
 * Anansium: A form of exotic matter that interacts with slipspace fields. Found naturally only in places where temporary slipspace portals can occur. Used in the construction of emissions baffles and stealth ablative plating used on prowlers, as well as certain instruments and superluminal communications equipment.
 * Aquaculture: the cultivation of aquatic produce for consumption (e.g. kelp, fish). Also called mariculture, aquaculture industries exist within both the human and Covenant civilizations, with the practice being particularly popular among the Kig-Yar.
 * Arco: Short for "arcology"; a dense urban habitat, often a single building or cluster thereof, designed to be self-contained and self-sufficient. Common on colonies. Sometimes enclosed and pressurized in the absence of a hospitable atmosphere.
 * Areophile: An enthusiast of Mars, Martian culture, history, etc.
 * Arterial Network: The collection of slipspace routes linking major hub worlds and hubstars within the Covenant empire.
 * Artificer: An emerging class of Covenant priest-mechanics following the Covenant War, specializing in syncretic technologies, or more specifically combining Covenant and human technologies.
 * Artisan: A class of specialized professionals within the Covenant civilization. Usually Sangheili. A prominent subset of artisans are artisan-armorers, responsible for forging weapons and armor.
 * Archkaidon (also Arch-kaidon): A title used in some Sangheili planetary and regional regimes for a feudal lord in charge of multiple lesser states. Analogous titles, such as High Kaidon, Kaidon Paramount, as well as various unique titles are also used regionally, often with various differences in their responsibilities and level of power over their subordinate lords. Usually, such nobles hold authority on a level ranging from a planet to several star systems, albeit with considerable devolution of power to their vassals.

B

 * Bauble: A type of spherical Covenant space habitat, sometimes mobile, with artificial gravity on most of the inner surface and lighting provided by a central plasma ball or shaft. Baubles range in size from under a kilometer in diameter to twenty kilometers or larger, though the vast majority fall within the sub-ten-kilometer range.
 * Belter: An inhabitant of the Sol system's asteroid belt, or more broadly, any Solar asteroid. Though also used more generally to refer to asteroid-dwellers in any system, "Belter" when capitalized formally refers to the populace of Sol's asteroids and their culture specifically. Denizens of non-Sol (or non-Belt) asteroids are often also called roiders or generally as spacers.
 * Biodisplacement: the act of relocating complex life from a planet and seeding it elsewhere. The inferred cause of out-of-place biota.
 * Bioforming: the alterations of Earth-based life (including humans) to adapt to an alien environment, or creating new forms of life (e.g. bacteria, algae) able to survive on an extraterrestrial world. Various bioforming techniques are a staple part of most terraforming efforts, with engineered algae and plants being used especially in the early stages. When applied to complex life such as humans, bioforming tends to be fairly subtle and mostly concerned with adaptations to different gravity conditions, or alien bacteria and viruses which may otherwise be lethal; humans cannot be remade to survive in a vacuum or withstand intense radiation, for example.
 * Biosuit A Covenant class of biomimetic skinsuit originating with the Sangheili, featuring thermal regulation and various life-support functions. Biosuits exist for use in both vacuum and in atmosphere. The biosuit helps maintain the wearer at a comfortable temperature, a feature especially important to the Sangheili in cold climates. Biosuits are worn under most patterns of Sangheili combat harness and are issued to other species' infantry in various capacities depending on role and rank.
 * Birddogging: The act in which point defense systems keep locking onto an undesirable target, typically one that poses little to no threat to the user.
 * Black glass: Covenant name for a mixture of Forerunner nanomachines and microchines with too many industrial uses to count. It is converted into an inert solid and pressed into tablets for exchange. In its active form it is used to patch, repair, and alter machinery. Direct exposure to black glass is highly hazardous, as the nanomachines target and unravel organic nerve cells for unknown reasons.
 * Blinker: A generic term for Covenant slipspace drives that trace their heritage to pre-Covenant Sangheili counterparts; also refers to early Sangheili FTL vessels. For details, see Covenant drive types.
 * Bought the farm: A common phrase in the various branches of the UNSC. It is a euphemism for soldiers who died or went missing in combat; see also "Went to the country").
 * Borer: Covenant slipspace drives derived from Forerunner technology, considerably more powerful than blinkers. Standard on most military and governmental vessels.

C

 * Carousel: A rotating section used to provide gravity on a spacecraft or station, or a station/habitat built around such a structure; see also Wheel in the latter usage.
 * Chameleoflage: A blanket term for photoreactive, non-field-based active camouflage technologies developed by humanity.
 * Chiiwe raahu: translated roughly as "Inner Path"; a reconstructed Solipsist sect of faith loosely based on the works of the mendicant-philosopher Qtaan the Far-Dreamer in the Covenant's classical antiquity; proponents maintain that the Great Journey can be achieved by moral and spiritual enlightenment alone, rather than technological means.
 * Cix-Tu: A minor alien civilization from the Covenant's galactic antispinward side known for their slavers, skilled surgeons and fairly advanced cybernetics
 * Cloud-jockey: General term for Kig-Yar communities living in floating aerostat communities, originally in the skies of Eayn and later other worlds, including some gas giants.
 * CMC: The Chikri-Merkaa Conflux, a post-Covenant polity.
 * Cold fusion: A popular name given to fusion processes capable of generating power at lower than natural temperatures, though still by no means room temperature (e.g. spin-polarized fusion); contrast with hot fusion.
 * Cometarians: Communities or individuals of human space miners who dwell on or in comets for any extended length of time, known for their often extreme isolation, harsh living conditions and consequent strange customs and cultures. Now mostly a historical term for several such communities in the early days of spaceflight, though some still retain their old lifestyles by choice.
 * Conciliator: A type of warrior-diplomat similar in principle to the role of the Arbiter, but more localized in their jurisdiction; later largely supplanted by the Prefects.
 * Concord: The Concord of Reconciliation, a league of several dozen post-Covenant groups championed by the Arbiter Thel 'Vadam; a kind of alien United Nations, and often just as effective at preventing conflict.
 * Congruents: A Covenant classification given to sapient species that share cognitive qualities broadly considered "normal". They all have an independent and self-contained consciousness and are capable of spoken language. Though not strictly a requirement, most also have a bipedal body plan. Similar to the human concept of anthroposophonts, or "humanoid" alien intelligences. Contrast with Enigmatics.
 * Conjunction: Covenant term for slipspace transit nodes.
 * Conservers: See "Planetary conservationism".
 * Coreward: The galactic cardinal direction pointed towards the Milky Way's core; contrast with Rimward.
 * Crimson Realms: A collection of Sangheili core system states considered to be in the direct cultural and political sphere of Sanghelios. See Crimson League below. Although the Crimson Realms and the Crimson League are not entirely synonymous, the distinction is academic from an external perspective.
 * Crimson League: A longstanding political alliance of many noble houses from the Crimson Realms. Has fractured considerably in the wake of the Great Schism, though remains powerful enough to form the core of the Concord.
 * Cryocomputing: Computing in extremely cold temperatures, often on cold worlds such as Titan
 * Csa'kishi: Sometimes translated as "stutter-song"; general name for ritualized Kig-Yar verbal confrontations involving aggressive and/or flamboyant posturing between participants (usually male) but rarely physical violence; evolved from lekking displays among males, and fulfills a social function of providing a nonviolent solution to otherwise bloody disputes
 * Cyberlife: An academic term used in reference to non-biological sentience; usually refers to smart AI, but can encompass other forms of artificial intelligence. Often used by pro-AI rights activists to highlight smart AIs' status as living beings.
 * Cynosure: A type of meditation-effigy used in the Covenant religion, representing a Forerunner deity or aspects thereof.

D

 * Dai'nos Yll: See Liturgical language.
 * Dead Fleet: A deactivated or dissolved UNSC Navy fleet which is retained in bureaucratic records for later resurrection.
 * Deck layout: The scheme by which a starship's decks are arranged. Traditionally, human ships have had "stacked" deck setup, with "down" being perpendicular to the main thrust axis similar to a skyscraper, with spin-gravity centrifuge sections being the exception. Some vessels following the advent of paragravity have adopted a hybrid or even fully thrust-parallel layout scheme similar to an airplane for various reasons. See human starship design for details.
 * Delugers: 22nd-24th century ideological group of pro-terraforming advocates who saw it as humanity's destiny to fill an otherwise barren universe with life. Also notable for launching a failed slower-than-light sleeper colony ship.
 * Demarchy: a mode of governance combining elements of democracy and anarchy. Common elements are understated (or at least redressed) hierarchies. Emerged into mainstream discourse in the 22nd and 23rd centuries; the Martian MIDA was one prominent manifestation of the ideology that eventually fell into extremism. Some colonies have demarchic societies, usually implemented via some form of online participatory governance; this is particularly common in small communities, such as habitats, though larger demarchic communities also exist, such as the former outer colony of Mesra.
 * Diocese: A type of Covenant domain directly governed by a Lesser Prophet and other religious authorities, established at many key reliquaries or industrial centers producing entrusted technology to ensure compliance to High Charity.
 * Disruptive Impulse: A Kig-Yar belief that society spawns delinquent individuals as a means of driving it forward/preventing stagnation, viewing chaos and delinquency as a necessary evil of sorts.
 * Directive: A legal act authorized by the UEG Senate which requires any named subjects to achieve a mandatory result, without dictating the means on how it should be achieved. They are often vaguely worded to grant freedom to the recipient, and noted suggestions are not enforced. The UEG's Directives pressed on the Outer Colonies were a major contributor to the civil unrest experienced before the Insurrection, as planetary governors implemented unpopular laws that allowed for abuse.
 * Domain: A general term for Covenant territorial units, defined by astrographic, historical and/or political factors. The most notable type, primary domains, were defined by both their direct administrative relationship to High Charity and generally standardized government structure. Primary domains could comprise up to 500 officially-recognized worlds and various lesser domains ranging from Sangheili lordships and their vassals to thrall-worlds, merchant republics and freeholds.
 * Downwell: Down a gravity well; on or to a planet's surface.

E

 * Elenchists: An initially derisive name given to a movement of human sympathizers among the Sangheili youth, who would then subsequently adopt it for themselves.
 * Enfold: Protectorates of the Concord of Reconciliation with minimal self-defense capabilities and limited representation in the Concord; often comprise colonies of the formerly lower client species, such as Unggoy and Kig-Yar. Fleets of the Concord proper are used to provide security (and, at times, humanitarian aid) in these territories.
 * Enigmatics: A Covenant classification given to aliens that, while undeniably intelligent, have sharply different physiological and cognitive qualities e.g. hiveminds, non-bipeds, and collective intelligences; contrast with Congruent.
 * Entrusted technology: A class of Covenant technology understood and manufactured only by High Charity or industrial centers under the direct supervision of officials of the High Council or Ministries; includes key strategic technologies such as Borer slipspace drives, long-range wavecaster communicators, and most high-end types of weaponry and countermeasures; see also Sanctioned technology and Native technology.
 * Esoterica: the name given to Covenant-developed technology where knowledge on its underlying principles have been lost; however, the ability to construct them is retained, usually only from select factories. Their adoption is spotty, and are usually featured in specific design patterns of warships, stations, equipment, and vehicles.

F

 * Fabricary: A Covenant factory, often one specialized for a given product (e.g. weapons, ships).
 * Farites: An anti-terraforming ideological movement started by the 22nd-century philosopher and spiritual guru Samudrasen Faries. Influenced by extant Conserver movements as well as paindeism and panpsychism, Faries proposed that Man should not meddle with extraterrestrial worlds in any way, as all of them may harbor the potential for developing life in the long term. Though Farites hold terraforming to be sacrilege, most schools accept the exploitation of asteroids and comets for the construction of space habitats, which also serve as the Farites' primary mode of residence outside Earth. At their most prominent in the 23rd and 24th centuries, very few Farite communities now remain, as theirs is largely considered to have be a cause long lost.
 * Fief (also fiefdom): a type of feudal land and property tenure within the Covenant, fiefs are mostly held by Sangheili nobles with the blessings of the Covenant government and range in size from a small patch of land on a planet to entire planets (the latter being more common on marcher colonies). In practice, most minor states within the Covenant are commonly called fiefdoms. Control of a fief came with various responsibilities, such as that over one's subjects. Regionally, fiefs were administrated and allotted by domain governments following the Second Illumination, which in turn coordinated with the Ministry of Integrity.
 * First Saints: The 70 San'Shyuum and Sangheili individuals of note who laid the groundwork for the Covenant faith and the Writ of Union, reconciling the myriad differences between the San'Shyuum and Sangheili religions into a unified theological framework; perhaps the most revered historical figures in the Covenant.
 * Forgeship: A type of Covenant industrial vessel housing assembly forges and/or fabricaries
 * Frankenship: A derogatory term used by UNSC Navy sailors to refer to ships with mismatched components.
 * Freeholder: A term used for Covenant citizens who own land and/or property, occupying one of several categories between menials/serfs and aristocrats; usually applied to Kig-Yar or Unggoy who live outside serfdom.
 * Fusioneering: The science and technology of controlled nuclear fusion for the purposes of power generation. A fusion technician is typically known as a fusioneer.

G

 * Gisord: A Covenant musical instrument that has its origins with the Sangheili; played with a gravitic-holographic interface.
 * Goshin-Kir: A Covenant board game of San'Shyuum origin, similar in concept to chess but much different in the particulars. It is a game of maneuver, with each side trying to pin down and expose the other side's regent. Goshin-Kir-related metaphors are sometimes used to describe certain political maneuvers, an example of this being the "Many games of Goshin-Kir" during the Great Schism, which saw factions attempting to use San'Shyuum politicians as figureheads.
 * Grand Council (also Grand Convocation): A large convocation of scholars and theologians from across the Holy Ecumene to debate on the finer points of faith, usually in response to major discoveries or new revelations. Generally seen as less partial than either the High Council or the Ministries; even if some of its members had ties to those bodies, they were rarely career politicians. Thus the Grand Council was seen as a kind of check on the power of the High Council, able to call into question even the Hierarchs' words.
 * Great Enemy (also the Enemy): Covenant theological concept representing, simply speaking, universal chaos, entropy and oblivion, the antithesis of the Great Journey. Most notoriously embodied by the Parasite and its many manifestations, though encompasses Mendicant Bias and other converted ancillas, internal strife, as well as wider moral and spiritual decline.
 * Great Spiral: Common Covenant name for the Milky Way.
 * Gryunjalla: An old Jiralhanae name for "Prospectors"; an elusive migratory civilization, elements of which supplied the Jiralhanae means for interstellar travel for a time in exchange for mining rights and labor; left the known regions of the Orion Arm centuries ago, though some suspect them to have kept an eye on the UNSC and possibly the Covenant up to this day.
 * Guild: A translated term for officially-sanctioned professional associations within the Holy Ecumene. Though several varieties exist, guilds can be broadly seen as something of a mix between a trade union and a cartel, regulating the practice and quality of their craft but also providing many secondary services and benefits for their members. Most legal professions within the Covenant sphere have guilds on both localized and empire-wide levels. Guilds wield varying degrees of influence, and some can be quite powerful in relation to entire subdomains of the Covenant or even the ministries themselves.

H

 * Hab: A habitat, usually space-based; also classically used to refer to habitation modules in older ship designs with clearly divided functional components
 * Habiforming: A non-anthropocentric counterpart term to "terraforming"; the modification of an environment (natural or otherwise) with the purpose of making it inhabitable for a given species
 * Hades Gulf (also Orion-Eridanus Gulf): a relative cavity in the interstellar medium partly adjoining the Local Bubble, which houses most of the human sphere. The Hades Gulf is also located between the human and Covenant spheres in the Orion-side half of FLEETCOM Sector 1. Home to the crossing routes Pleiades Corridor and Stygian Ingress, as well as an increasing number of both human and post-Covenant colonies and activity in the post-war decades.
 * Halcyon Rift: Covenant designation for the larger interstellar void comprising the Local Bubble and the Hades Gulf; as the region is located at the very fringes of Covenant space, they have no established nomenclature for its constituent elements.
 * Har Tanqi: A school of Covenant calligraphy that favors ovoids, circles and other curved forms
 * Heavyborn (also born heavy, heavyworlder): a moniker for people born on high-gravity worlds such as Reach, generally resulting in a particularly sturdy bone structure and build. See also lightborn.
 * Heterodox: Variants of the Covenant religion which fall outside of mainstream or orthodox teachings, but do not run counter to orthodox teachings. Can also refer to secular or cryptoreligious ideologies and organizations that are not derived from worship of the Forerunner.
 * Hidebehind: A class of transient sensor phenomena often encountered in deep space.
 * Holy Ecumene: a common Covenant name for the Covenant's religio-cultural sphere of influence.
 * Hot fusion: The name given to fusion processes that operate at natural temperatures. Common before 2505, they are usually known for being cheap, bulky, and have a low power output; contrast with cold fusion.
 * Hubstar: a stellar system with access to particularly auspicious slipspace pathways; comprised the Arterial Network. Also called Keystone systems.

I

 * Ikjuttar: A secretive and isolationist fringe culture confined to their home system in the anti-spinward side of the Covenant Empire, they have evidently never been seen or interacted with in person.
 * Impulse drive: A generic term for spacecraft maneuvering engines that use thrust to move the ship (as opposed to gravitic or faster-than-light engines), though usually used to describe alien forms thereof (e.g. repulsor engines). Also called a reaction drive.
 * Incorporated intelligence: A form of non-volitional AI used in fringe applications by the Covenant, incorporated intelligences are constructs locked to a single substrate and incapable of directly communicating with other computers. Incorporated intelligences are meant to circumvent the heresy of associated intelligence, which is widely interpreted as a thinking machine capable of networking and growth.
 * Inner Colony Wars: A series of conflicts fought mainly over settlement claims, political differences and terraforming methods on the worlds of humanity's early interstellar empire in the late 24th century.
 * Instrumentalism: A mainstream doctrine of the Covenant religion, stating that salvation is only possible through technology, specifically Forerunner technology (though some historical sects extend this to any technology). Contrasted with Solipsism, which is widely deemed heretical.
 * Interstellar Jump Point (IJP): A region of space within a star system that serves as the entrance for one or more charted sliplanes. Typically a Lagrange point of a large planet and a star, with the trojan points being the most common. IJPs in developed systems often house infrastructure to service incoming or outgoing ships, such as port stations and fuel depots. They may periodically become non-viable due to gravitational interactions between planets on their orbits.

J

 * Jehioi: Sangheili word for "Wayfarers"; a pre-Covenant civilization that evidently established outposts within the Orion Arm approximately 40,000 years ago, all of which have long since been abandoned and reduced to ruins.
 * Joint-Occupation Zone: A formally-defined region of space with shared jurisdiction between the UNSC and the post-Covenant polities allied with it, mainly the Concord of Reconciliation

K

 * Kaichen: The female equivalent of a Kaidon.
 * Khai'ul: Literally "Sacred Geometry"; the field of Covenant theology concerned with the study of Forerunner architecture and design, its patterns and peculiarities, and the divination of purpose and wisdom therein.
 * Kilolight: Colloquial term for kilolightyear; one thousand lightyears
 * Konta: A type of Sangheili dance performance. Kōnta dancers pride themselves on highly synchronized choreographies and impressive neuromuscular control.

L

 * Lakaharusi: Literally "water tradition", this is a Covenant school-of-thought that encourages a world's population to seek a closer connection with their natural environment. This prevents the construction of large-scale cities, with most buildings instead being accessed from the waterways.
 * Lamesai Unesh Nok: A Covenant liturgical tongue term for the Enemy; see Great Enemy
 * Legate: An ecclestiastic official, often a minor prophet or ministry staffer, sent on a special ambassadorial mission. Often attached to a Covenant fleet or regional government.
 * Lekgoforming: A process engaged in by some Lekgolo meta-colonies in which a world is gradually shaped to fit that colony's preferences, typically involving extensive excavation processes. The process can take centuries or longer, and rarely truly stops.
 * Lensor field: A type of energy field used to bend light. Such fields were used by the Covenant, among other things, to create magnifying devices, components of various sensors and communication systems, and active camouflage.
 * Lesion: Covenant term for a volume of space exhibiting a range of anomalous phenomena, ranging from unsettling psychological effects to immediate physical dangers which may be difficult to quantify. Lesions are often irregular in shape and even their true scale can fluctuate.
 * Lesser Ring: Covenant name for a class of ring-shaped Forerunner civilian habitats unconnected to the Halo Array.
 * Life engine: A type of Covenant terraforming (or habiforming) machine, derived from a Forerunner equivalent
 * Light: Colloquial spacer term for lightyear; see also kilolight.
 * Liturgical language (Dai'nos Yll): a Covenant language used in religious and high-level political contexts. Rich in nuance, depth and complexity, it traces its roots to the ceremonial language once spoken by the San'Shyuum Reformists, itself a bastardization of a Forerunner archival language.
 * Lightborn (also lightworlder): a person born and raised in low gravity, typically resulting in a light and tall build. Without medical amenities, such individuals may suffer from various developmental defects, though virtually all modern human habitats use some form of artificial gravity to avoid the detrimental long-term effects of microgravity. Still, the level of artificial gravity varies, and is often below Earth-standard even on many colony worlds. Individuals from such worlds typically find it difficult to acclimatize to higher-gravity environments and may require additional medical intervention when doing so. See also heavyborn.
 * Lobber: colloquial name for a payload-delivery mass driver, usually civilian/commercial
 * Loremaster: Covenant term for a scholar or scientist, usually one devoted to a specific branch of "lore", or academic/scientific discipline. After the onset of the Great Schism, many loremasters have taken it upon themselves to preserve the Covenant's historical and cultural knowledge.
 * Looters: A hypothesized, presumably migratory pre-Covenant civilization whose most notable act was to strip a considerable number of Forerunner reliquaries clean of usable technologies and data millennia before the rise of the Covenant; may actually have been more than one civilization. Formally called Optem.
 * Lostech: A term used by humans for some high-end technologies that are no longer possible or feasible to manufacture following the Human-Covenant War, due to the loss of the relevant infrastructure or expertise. Most applicable on remote colonies, though some higher technologies were unavailable to the UNSC for a time after the war due to the breakdown of industry and supply chains.

M

 * Magistrate: The chief San'Shyuum governor of a primary domain.
 * March: A fringe region of the Holy Ecumene.
 * Mass driver: A large ground- or space-based coilgun used to launch payloads into space or across a system. In groundside applications, most mass drivers comprise a fixed acceleration channel up to dozens of kilometers in length. Though commonly understood to refer to the civilian applications of the technology, the term "mass driver" is sometimes used to refer to large magnetic linear accelerators in general.
 * Merfolk (also Phibians): A conspiracy theory positing the existence of one or more extremely altered populations of humans adapted to aquatic or amphibian life, originally centered around the subsurface ocean of the Jovian moon of Europa but later expanded to extrasolar worlds with the Domus Diaspora. Depending on the theory, these creatures are either the product of self-modification on part of aquatic-oriented 22nd-23rd-century Technarchist groups, or horrific experiments on part of the Frieden or the UEG.
 * Meta-civilization: A collection of multiple civilizations that are mutually distinct but related on a high level, e.g. sharing a common origin and/or ideology. Examples include the Covenant and humanity.
 * Mimic: A type of surveillance ship built from an existing civilian hull, which eschews stealth in favor of blending in with shipping.
 * Missive: Covenant term for a formal wavespace transmission.
 * Moon rabbit: Early slang for a Lunar colonist, suggestive of their rapid population growth, with further implications as to the peculiarities of the colony's sexual mores.
 * Muratovski effect: A phenomenon where energy released into slipspace has a tendency to scatter into low-level microwaves in realspace, which hampered early attempts at developing slipspace communications. Has since found use in starship heat management as well as prowler cloaking systems.

N

 * Ngaeha'eewoi: Sometimes freely translated as "honor-in-blood"; a diverse set of Sangheili cultural traditions governing the accepted occasions for the spilling of blood, as well as acceptable forms of medical treatment. The most hardline interpretations of these traditions, observed by select clans and warrior orders (mostly Zealot chapters), notoriously include strict taboos around medical treatment, specifically surgery. More moderate and common interpretations merely make a distinction between "blood spent and blood wasted", with a stigma on injuries resulting from foolishness or carelessness.
 * Nanolam: Short for nanolaminate; human name for a category of Covenant hull composites constructed in ultrathin layers.
 * Native technology: Technology originally developed by each client species, which (barring cases of forbidden technologies like AI) often remains in use well after that species' incorporation to the Covenant collective and may, in select rare cases, become adopted by the Covenant at large. However, most native industry is eventually drowned out as a byproduct of the assimilation process and replaced by Covenant mainstream technology.
 * Neurodeath (also neural death): A state in which the brain has suffered mortal oxygen deprivation to the point of being irrecoverable by modern medical science. Usually regarded as an individual's legal death.
 * Neurohelmet: A type of removable neural interface built into a helmet, used by Covenant pilots to operate their strikecraft. While bulky, they are safer and easier to upgrade than neural laces.
 * Nilatite (Qerenoka: Nilat'uni): Covenant classification for gravitogenic materials, such as Zenostium and Tyrkal; name is derived from Nilat'i, an ancient Sangheili goddess of gravitation, orbits and rotation, the inevitability of things, and the patron deity of dancers.
 * Nomisma (Qerenoka: Jiile) A generic word for currency used in the Covenant Empire. Although multiple currencies were in circulation throughout the Human sphere prior to the war, the bewildering variety of coinage used by the Covenant defied easy categorization.

O

 * O'Neill: An O'Neill cylinder; a type of human space habitat based on Gerard O'Neill's 1976 Island Three concept.
 * Outer Vigil: signatory polities of the Concord of Reconciliation close to the Covenant periphery that engage in relatively close military and security cooperation with the core Concord. In some cases, the Concord's authority over Outer Vigil polities is more symbolic than anything.
 * Outliers: rogue societies that existed outside the Covenant's hierarchy, usually having escaped the hegemony's grasp by fleeing beyond the Covenant's peripheries. Outlier communities were rarely larger than a single planet and not often successful in the long term, most of them either falling to internecine conflict and/or being re-assimilated as the Covenant expanded.
 * Out-of-place biota: Species of fauna and flora that are discovered on planets they clearly did not originate on.
 * Orka'Chuh: A species of four-legged reptiles domesticated by the Sangheili as both pets and work-animals; often compared to Earth's dogs. Dozens if not hundreds of breeds exist for different looks and purposes.
 * The Others: A possible alien civilization potentially of equal power and reach to the Covenant inferred from various Covenant records throughout history; as contact with them was rare, information on them or their current status is extremely scarce.

P

 * Paleotechnology: technology created by Antecedent civilizations, or by the currently active cultures in their ancient past. Most examples of paleotechnology found in the galaxy have long decayed beyond any hope of functionality, with many ruin sites having long been stripped clean of useful technologies. The Forerunners are a notable exception to this as many (albeit not all) of their technologies are remarkably time-proof, though even in their case, intact examples are rare and usually found in installations with robust self-repair systems.
 * Paragravity: a type of synthetic gravity induced via field-based means, i.e. not thrust or centrifugal force. Became commonplace on human ships in the 25th century. Encompasses inertial compensation.
 * Pax Humana: A much-romanticized period of human history marked by expansion, prosperity, and optimism, generally agreed to have begun following the Inner Colony Wars in the early 25th century and lasted up until the Insurrection in the 2390s.
 * Peripates (also Migrants): the segment of the Covenant population that remain largely on the move aboard ships or mobile habitats, rather than fixed worlds; can also apply to those ships or habitats in question. Despite their eclectic nature, the Peripates is sometimes understood as a distinct subculture and/or faction.
 * Phalera (plural Phalerae): a Covenant translation device, often ornately decorated and worn as jewelry. As the Covenant's empire is vast and encompasses dozens of languages, such translation devices are necessary to facilitate communication.
 * Phoenix Initiative: An interim governing body created by the UNSC and various colonial governments and corporate entities to manage human reconstruction and resettlement after the Human-Covenant War; replaced the UEG as the primary human government in the Reconstruction era.
 * Phyle (plural phyles or phylae): One of the ancient tribal/cultural groupings that are regarded by tradition as the populations all Sangheili today descend from. The concept has also found its way into broader Covenant xenoanthropology and is sometimes applied to other species' (especially the Kig-Yar's) "root" ethnic groups.
 * Pioneers: General term for the extrasolar human colonists of the first wave, beginning in 2310 and ending with the onset of the Domus Diaspora in 2562. Although their conditions varied greatly from world to world, the Pioneers shared a certain common pride especially in contrast to newer settlers who later arrived on their worlds; the Pioneer identity was formed largely in contrast to the "Diasporans" of the second wave.
 * Pipeliner: A vocation in the Covenant empire, similar to an electrician or an instrumentation technician. Calibrates or repairs networked sensors and controls. Although pipeliners work with sanctioned technology, their work is tightly constrained so that they cannot make forbidden innovations or networked computers.
 * Planetary conservationism: The belief that extraterrestrial worlds should be left as untouched and undisturbed as possible, often on scientific grounds. Even if human settlement occurs, planetary conservationists - or Conservers - maintain it should be heavily regulated and preferably take the form of self-contained arcologies. Conservers mainly oppose the terraforming of worlds with existing, past or primordial biospheres, often for reasons of scientific study or simply for the inherent value of alien forms of life. Many also cite Earth's ecological crisis in the 21st-24th centuries as a cautionary tale against unchecked expansion. Contrast with Ploughers.
 * Pleiades Corridor: the most widely trafficked slipspace route used to cross between the human and Covenant territories post-war, named as such for its proximity to the eponymous star cluster. Known to the Covenant as the Kelsac Passage after the Kelsac Periphery, its starting point within the Covenant sphere.
 * Plenarites: A sociological movement in the 23rd and 24th centuries which warned against interstellar colonization shattering humanity's social and cultural cohesion, and instead proposed that human habitation be concentrated in SolCore within a minimal communications lag range; a proposed long-term solution for population expansion was to construct a vast network of artificial worlds and habitats around the Sun, termed the One-Hour Girdle after the proposed maximum communications lag of one hour; this habitation-swarm could potentially house the human civilization for up to millions of years to come. The Plenarites were largely ignored and fell into obscurity after the gold rush to the stars truly began with the Domus Diaspora.
 * Ploughers: A term for those advocating for terraforming and the wholesale exploitation of a world's resources, either in a specific case example or universally; contrast with Conservers. Originally a neutral or even positive term that carried connotations of a pioneering spirit, it later came to be used accusingly by opponents of unchecked settlement.
 * Ploughship: A category of Covenant vessels equipped with Forerunner slipspace drives, designed to drag flotillas of smaller vessels in their wake much faster than normal ships.
 * Possum: Nickname for Portable Spartan Support Module, or PSSM; a mobile container used to support Spartan supersoldiers in the field and/or outside dedicated facilities, containing an armor repair room and/or field infirmary.
 * Precarium (plural precaria): Translated name for a type of temporary land/property grant within the Covenant Empire. Often issued to "lesser" species such as Unggoy or Kig-Yar, ownership of precaria was less secure than that of a fief.
 * Prefect: The head of a Quaestor prefecture.
 * Primalism: A cultural trend within the Covenant's San'Shyuum elite, favoring "primitive" or less sophisticated and intricate customs than those of High Charity's upper classes. Became prominent preceding the 9th Age of Reclamation.
 * Proscription Against Particular Revelation: A key principle of the Covenant religion holds that any holy discovery or revelation is only valid if they can be independently demonstrated. The Covenant faith is founded upon careful analysis of incomplete and time-corrupted records. Careless recovery could damage or destroy these volatile records. Likewise, unprincipled clerics could make a career out of fabricating new finds. Despite the Proscription, false revelation could at times be legitimized by forgery, public support and/or political maneuvering, as demonstrated by the rise of the last Hierarch Triumvirate.
 * Protectorate: A UEG political division and electoral district, formed out of a geographic and political bloc of national territories. The Sol system was broken up into 49 protectorates.
 * Purp:
 * An alleged form of crystallized Sangheili blood used as a potent narcotic, based on an urban legend that circulated throughout the Inner Colonies in the early 2560s. Some conspiracy theorists claim that "Purp" is secretly supplied by the Concord to the UNSC leadership to keep them "compliant". The psychotropic effects of Sangheili blood, crystallized or otherwise, are completely anecdotal.
 * A nickname for ex-Covenant individuals, particularly ones of lesser repute. Supposedly originated from post-war law enforcement slang on some worlds to refer to criminals (or suspected criminals) of ex-Covenant origin as a play on "purple" and "perp".
 * Purple zone (also purple district): A colloquial term for urban districts or regions on human worlds inhabited by significant ex-Covenant populations.

Q

 * Quadrant (also Supersector): The highest division of space used in the Human Sphere; there are four in total, with the name of each corresponds to the most famous constellations found in their direction, as seen from Earth.
 * Quarter: one of the divisions of space used by the Covenant, with the entirety of the Covenant Empire being split into four quarters; these are named after their galactic directions from Sanghelios.
 * Quaestor: a class of Covenant law enforcement officers.

R

 * Raan-Uchaal Bridge: The Covenant name for the Orion Arm; the Raan Spine and Uchaal Wing are the Sagittarius and Perseus Arms, respectively.
 * Reader: A member of the Covenant ecclesiarchy who preaches sermons and interprets scripture for the masses, regardless of rank.
 * Remembrance coin: A metal coin memento, given to the family of dead UNSC Navy sailors.
 * Refu: Short for "refugee"; generally regarded as a slur and used in the plural "refus", a homophone for "refuse". Prominent particularly on Earth in the later half of the Human-Covenant War and afterward.
 * Relic-reader: A monastic class of archaeologists responsible for deciphering the purpose and nature of Forerunner relics or reliquaries, as well as interpreting Forerunner records. Most were in the employ of the Ministry of Etiology.
 * Restricted volume: A defined area of space under Space Traffic Control (STC) restrictions, imposing various limits on maneuvering and control, which vary regionally. Includes e.g. interstellar jump points, the orbital space of most developed worlds, and the vicinity of spaceports.
 * Retrograding (also retrograde burn, turnover, reverse thrust): A maneuver in which a spacecraft applies thrust to counter its existing velocity. As most ships lack large forward-facing engine units, this is usually accomplished by flipping the entire ship around and using the main drive(s) to brake.
 * Revanchists: A post-war human political movement pushing for retribution against the post-Covenant, particularly the Sangheili. Rather than a single group, the Revanchists are a broadly-defined movement encompassing groups of varying size and political influence. Examples include the Sapien Sunrise.
 * Rhuumo: A difficult-to-translate Sangheili concept that can be understood as the integrity of a social group. A tribal or clan-based polity generally has a higher cohesion than a large, state-based one, but since the transition to larger political units is inevitable for progress, states must seek to preserve or emulate the binding mechanisms of smaller units (e.g. values, tradition, and honor). Rhuumo is a measure of the success of integration of ethics and social bonds from the old to the new, or the "scaling of that which was once thought unscalable". The amount of rhuumo a civilization has is said to have direct implications on its resilience and lifetime, among other things, so much so that it is often called the pillar of a culture.
 * Rimward: The galactic cardinal direction that points towards the outer edges of the Milky Way; contrast with Coreward.
 * Roiders: Colloquial human term for asteroid-dwellers; sometimes carries assumptions as to the culture or psychology of such individuals or communities. While ostensibly derived from  ' roid as a contraction of "asteroid", the term has also been suggested to relate to the steroids required for proper muscle and bone growth in low-gravity communities. See also Belter, which (at least when capitalized) is regarded as more specific to those living in the Sol Belt.
 * Rock (also burrow or warren): A habitat built into an asteroid or similar object; also used to refer to asteroids in general.
 * Rockhound: Nickname for asteroid prospectors, or more broadly, space miners.
 * Rookery: A large cluster of Kig-Yar families who are not necessarily related, but started having children around the same time and built a community to house those families. Rookeries are a growing trend in the large cities of Dasim, but by and large the population of that province is organized into clans.
 * Rooted: A term used by Peripates for populations whose dwellings are fixed in a given system. Also Placid.
 * Ruugahari: Literally "Soul-denial"; the most extreme form of anathema issued by the Covenant, which decrees that a species is unclean and without soul, and should be exterminated for unforgivable blasphemy (such as purposeful and widespread destruction of holy relics). First applied against the Lekgolo and later humanity; annulled in both cases, in the latter case by the Concord's first Grand Council in 2554, on the grounds that the Hierarchs had no demonstrable justification to issue the anathema in the first place, and likely did so for personal gain.
 * Ruuk: Corpse in Qerenoka, generally used in neutral contexts. Derivatives include Na'ruuk (an esteemed figure brought back to life), Soruuka (honored or familial dead), and Kitar'ruuk (a reanimated corpse taken over by demonic spirits).

S

 * Sanctioned technology: Covenant technology that can be manufactured or repaired by the Holy Ecumene at large with the blessings of the Prophets. Includes most non-strategic technology; the majority of mundane technological appliances, Blinker slipspace drives, short-range FTL communicators, and so on. Most sanctioned technology originates in the realm of entrusted technology; how long it takes for entrusted technology to become sanctioned is decided entirely on a case-by-case basis.
 * Schismatics: General term for the individuals and groups who stood in opposition against the Hierarchs during the Great Schism; largely encompassed Sangheili or Sangheili-led groups and forces; initially known to the UNSC as Separatists.
 * Scuttlers: A (sometimes derogatory) name for several centuries-old populations living in massive warrens within the ice sheets of the Jovian Moons of Europa and Ganymede. Many wouldn't leave their dark, damp and cramped homes even with the advent of slipspace travel and the possibility of settling earthlike garden worlds.
 * Seastead: A dwelling built at sea, traditionally in international waters; typically also refers to the associated community. Usually taking the form of a self-sufficient arcology or a complex thereof, this method of habitation was at its height on Earth from the late 21nd to the early 23rd centuries. Since the advent of the UEG and the onset of interstellar colonization, many of these structures have emptied and fallen to disrepair, though some communities remain, and the steads themselves go in and out of fashion as retreats for the wealthy seeking a different life outside Earth's metropoles. Seasteads also serve as the primary form of habitation on several colony worlds with no natural landmasses. Some Covenant worlds have equivalent structures.
 * Second-Sundog: A colloquial name for a freighter-turned-racing craft; inspired by the successful career of the Parhelia.
 * Servitor:: Common name for robots and drones used by the Sangheili before the advent of the Covenant. The Covenant's anti-AI strictures would later see the servitors disappear from the Sangheili civilization. Certain types of Lekgolo colony harness were derived from servitor shells.
 * Shal'annu: A system of formalized assassin-warfare common in Sangheili feudal politics. Originally conceived to limit outside casualties, it is now a highly ritualized affair rife with tradition.
 * Shon'ai: A Sangheili term that literally if loosely translates to 'Whatever will be, will be.' It means accepting fate and acting in the moment, and it is a core part of what they call valor. The Sangheili have built martial disciplines around it, most of which seek a zen-like state in the middle of combat. This is a battle trance where reaction is immediate and without hesitation, and many practitioners report taking action without even realizing what they hope to achieve, as if their motion is commanded by a higher power.
 * Siakar: An avian creature native to Nesarok, one of the Sunlit Worlds; also the name of a constellation on that world, which inspired the naming of the Siakar Expanse.
 * Siakar Expanse: A Covenant primary domain notable for its proximity to the human sphere beyond the Pleiades Corridor crossing route.
 * Sikwalo (also False Unicorn): A species of deer-like mammals that have a pair of smaller horns on the nose, with males bearing a single larger one on their foreheads. They are a very common example of out-of-place biota, found in both the Human Sphere and Holy Ecumene.
 * Simulacrum (plural simulacra): An (usually dumb) AI simulation designed to impersonate a living individual, for purposes of entertainment, leisure, therapy, simulated telepresence and more. Strict laws govern the use of simulacra, and the malicious use of the tech has prompted the development of increasingly strong authentication methods to prevent identity theft. Legal simulacra used at the behest of the individual being impersonated are also known as surrogates.
 * Skyfall: A mythologized (but evidently historical) cataclysm in the Sangheili's ancient, planet-bound history which instilled in the species a widespread taboo against tampering with Forerunner artifacts.
 * Sliplane: A pathway between two points in normal space through the hyperspacial interstices of slipstream space; a slipspace route. The "higher" the "layer" of slipspace, the more efficient will the lane be in terms of speed, energy expenditure, and strain on the drive.
 * Slipliner: Early human term for a slipspace-capable craft, usually a large one such as a colony ship.
 * Slipper: A now-extinct occupation of explorers who charted the fastest and safest slipspace routes during the early days of extra-solar expansion.
 * Slipwave: an EM-spectrum broadcast propagated through wavespace; used in reference to wavespace communications.
 * Smatter: Short for smartmatter; a form of programmable matter used in some Forerunner construction.
 * Solar Millenary: The 1000-LY-radius-bubble around Sol; arbitrary as a division of space outside its relevance to humanity in the post-war era, with human settlements being established further and further across this region.
 * SolCore: Humanity's home system, Sol, and its immediate surroundings within a five-light year radius; one of the three main categories of human colonies, the other two being the Inner and Outer colonies. In both academic and colloquial use, "SolCore" also refers to the people (sometimes the political and/or commercial elite) of said system.
 * SolNet: Sol's internal communication network.
 * Solipsist: A broad term used by the Covenant for religions or philosophical movements which explicitly emphasize immaterial pursuits such as meditation, rather than technology, as a means to salvation or enlightenment. Such movements were, virtually without exception, regarded as heretical by the Covenant ecclesiarchy, as they were deemed to disregard the "instruments of the divine", which were understood as a necessity for salvation in all officially-sanctioned brands of the Covenant faith. Some solipsist traditions, such as Raah Chïwei, retain the trappings of the Covenant religion, while others, such as the Faith of Ien-Djyrn, are entirely distinct religions. Contrast with Instrumentalism.
 * Spacer: An individual living and/or working in space.
 * Spanner: A nickname for Kig-Yar who spend most of their lives in microgravity and have elongated bones as a result, resulting in a gangly overall appearance. They were usually families of mechanics and such who spent all their lives in space and had little desire to return to the crushing embrace of gravity. C.f. Spacer, Roider, or Belter.
 * Spatial Combatant: Any given warship whose primary purpose is to defeat enemy ships with hull-mounted weaponry, whenever they be missiles, guns, or energy weapons.
 * Spindle: A name sometimes given to cylindrical space habitats, either classical O'Neill cylinders or variations thereof; see also O'Neill.
 * Spinward: A galactic cardinal direction that points towards the natural rotation of the Milky Way; contrast with Trailing.
 * Starshield (also Starbinder): A type of Forerunner device used to arrest a star's life cycle, typically for the purposes of preventing it from entering a giant or supernova state. Toward the end of the Forerunners' struggle against the Flood, many such machines failed, either deliberately or by sabotage, leaving in their wake systems scorched by novae.
 * Steaders: Short for "Seasteaders"; a human subculture focused on living permanently at sea, sometimes characterized by utopian social goals and/or disdain for traditional governments (see Seasteads); at its height from the 21st to the 22nd centuries, after which they largely lost their original purpose with the muddling of national boundaries under the UEG, though some of Earth's remaining seastead communities retain vestiges of their old utopian ideals.
 * Summons to Reconciliation: An edict passed by a senior official in the Covenant hierarchy, declaring that an Heterodox belief has crossed into the realm of heresy, and its adherents are to reform or abandon the belief lest they face prosecution.
 * Sundering Years: A common name for the post-Covenant War decades, encapsulating the general trend of splintering among both post-Covenant and the human sphere.
 * Sunlit Worlds: The oldest and most powerful Sangheili (and by extension, Covenant) worlds, named as such for their relative proximity to Urs, whose light can still be seen with the naked eye from these worlds. The Sunlit Worlds are mighty indeed, and several of them are of an equal standing to Sanghelios as political and cultural centers.
 * Suspensor: Covenant term for an anti-gravity unit.
 * Swarmworld: Covenant term for a category of worlds reserved for, and mainly colonized by, Lekgolo. The Lekgolo societies on swarmworlds largely existed across vast underground caverns, and were largely isolated from even the rest of the Covenant at large; outsiders stepping foot on such worlds was considered both exceedingly rare and hazardous.
 * Swords of Sanghelios: A martial order based on Sanghelios, which acted as the de facto government of that world for a time. One of the core polities that comprise both the Crimson League and the Concord.
 * Synod: The administrative council of a primary domain, consisting of local aristocracy, representatives of the Ministries, as well as the domain's Magistrate.

T

 * Take the hills: A slang term for sexual intercourse, commonly used in the UNSC's special forces community. It was popularized by Lieutenant Sherry Friday, who evidently thought that the UNSC had enough depressing landscape-related euphemisms.
 * Techary: A class of priest-mechanic within the Covenant capable of repairing or constructing entrusted technology within their fields of specialty.
 * Technarchists: A human ideological movement at its most prominent in the 23rd-23th centuries. The Technarchists were transhumanists and social utopians pushing for de-regulation of technological progress, particularly in areas of AI, cybernetics and genetic and bio-engineering.
 * Terraforming:: the process of altering an alien planet or moon to be more suited for Earth-based life, or more broadly, the preferred living conditions of the party responsible. Also known as ecoforming when performed by non-terrestrials. C.f. Bioforming.
 * Thallit: A calming narcotic consumed by Kig-Yar in the form of sticks; c.f. cigarettes. The active ingredient in Thallit is a substance that calms and focuses the mind.
 * The Tribulations: A latter-day historical name given to the turbulent first decades of the Concord of Reconciliation and its struggles to establish itself.
 * Torchdrive (also fusion torch): A colloquial term for a fusion drive. Marked by a combination of high thrust and high efficiency compared to traditional drive types. Fusion-powered ships were historically known as "torchships", though this term is now less frequently used as the sheer novelty of the technology has long worn off.
 * Trih Xeem: Covenant term for the act of prematurely inducing a supernova, or alternately a Forerunner device (or array of devices) designed for doing so. The term is based on an archaic Sangheili dialect, and supposedly means "Absolute Cleansing".
 * Trailing (also trailward or anti-spinward): The galactic cardinal direction that points away from the rotation of the Milky Way; contrast with Spinward.

U

 * Ulterior: Umbrella term for civilizations that existed outside the Covenant's influence.
 * United Earth Space Corps: The collective name for the space-based arms of the UEG, including the UNSC, the former CMA, and a number of smaller departments; now largely a historical term used only in ceremonial contexts.

V

 * Valuun: Qerenoka for "devotee" or "zealot"; native name for a Sangheili Zealot. Sometimes spelled Baluun due to dialectal variance.

W

 * Wavecaster: Covenant name for a wavespace transmitter, a device enabling faster-than-light communication.
 * Wavespace: Collective term for infinitesimal slipspace pathways optimal for the transmission of electromagnetic radiation, but unsuited for matter transit. Like normal slipspace, there are many (perhaps an infinite number) of "layers" to wavespace stacked atop one another, each more efficient than the last. Interface resolution, energy, and computing power are the main limitations to accessing higher layers. While humanity has had the theory of wavespace for centuries, communication through it only became viable on a mass scale in the mid-26th century with the capture of Covenant technology.
 * Wayfarers: See Jehioi.
 * Wayfinder: A class of Forerunner navigation computers as categorized by the Covenant; however, seems to refer to more than just one type of discrete computer system.
 * Went to the country: A phrase commonly used by members of the UNSC to refer to servicemembers who committed suicide; see also "Take the hills". "Remember Franks from Fort Nefry? He's gone. I heard that he went to the country to be with his wife and kids."
 * Wheel: A human space station or habitat based upon a rotating carousel section providing centrifugal gravity. Usually structured like a literal wheel, with spokes leading from the outer carousel to a central hub, which typically houses the main docking as well as control facilities. Some such stations include more than one wheel, as well as additional structures for functions like hydroponics, etc.
 * Windweaver: A Covenant techno-artisan specialized in climate engineering
 * Word of the Second Sunrise: A Covenant holy book which serves as the foundational text for the Covenant religion
 * Worldship (also megaship): A large Covenant ship or mobile station housing the population of a small world; typically, such ships have other functions besides habitation, such as resupply, refit and mining. By far the largest and most notable example is High Charity, though there were numerous smaller city-stations within the Covenant. Refit and replenishment stations with habiformed recreational areas (such as the Unyielding Hierophant) are also often regarded as worldships.
 * Worldweb: A planetary-scale data network. Virtually all worlds maintain their own information nets, communicating with other worlds' networks through incredibly complex protocols. Any communication with other worlds' networks has historically been subject to light lag and the refresh delays inherent to the use of data-courier ships traveling to and from other systems, though this changed with the advent of superluminal communications in the mid-26th century. Developed systems have their own "meta-networks" encompassing the worldwebs of each colony there, with Sol's being known as SolNet.
 * Worm-lords: Covenant term (sometimes derisive) for Sangheili clans acting as attendants for a Lekgolo lineage. The bonds between such clans and their Lekgolo charges were deep and often ancient, and they formed their own kind of secret subculture within the Covenant.

X

 * Xar-Shaa: An aquatic species with a minor interstellar sphere of influence in the antispinward Sagittarius-side edges of the Orion Arm, partly overlapping with the Holy Ecumene proper. Part of the Covenant fringe. Slow, difficult to communicate with, and requiring cumbersome environment suits to operate in a normal atmosphere, their contribution to the Covenant largely involved handing over the few Forerunner artifacts they discovered, to which they exhibited a curious disinterest.

Y

 * Yonhet: A species of amphibious tripods native to the moon of Yonhe. Part of the Covenant fringe.

Z

 * Zenither: Demonym for the Covenant hub world Radiant Zenith.