Glossary
The words the subject uses, defined plainly. Each entry says how the term is used in the literature, what the sceptical reading is, and where in the Atlas to read more. A definition here describes a claim; it does not confirm one.
- AARO
The Pentagon's All-domain Anomaly Resolution Office, created in 2022.
The All-domain Anomaly Resolution Office is the US Department of Defense unit that collects and investigates reports of unidentified anomalous phenomena across air, sea, space and under water. Its 2024 historical review found no evidence that any US programme had recovered extraterrestrial technology, and it attributes most resolved cases to balloons, drones and sensor artefacts.
- AATIP
A Pentagon programme, 2007–2012, that studied unexplained aerial reports.
The Advanced Aerospace Threat Identification Program was funded at the request of Senator Harry Reid and run largely through a Nevada contractor. Its existence became public in December 2017 through a New York Times story, which also released Navy infrared videos and reset the public conversation around the neutral term UAP.
- Abductee
A person who reports having been taken aboard a craft against their will.
The word entered general use after the Betty and Barney Hill case became public in 1965. Some experiencers prefer the term 'experiencer' because it does not presume what happened. Abductee accounts typically involve missing time, a medical examination, small grey beings and a memory that returns in fragments or under hypnosis.
- Abduction phenomenon
The body of reports, since 1961, of people being taken aboard craft and examined.
Researchers such as Budd Hopkins, David Jacobs and John Mack argued that the reports form a consistent pattern; psychologists such as Susan Clancy and Richard McNally have shown that sleep paralysis, suggestion and cultural imagery can produce the same pattern. The Atlas presents both readings.
- Ancient astronaut hypothesis
The idea that visitors from elsewhere shaped early human civilisation.
Popularised by Erich von Däniken's Chariots of the Gods? (1968) and Zecharia Sitchin's The 12th Planet (1976), it reads myths, monuments and religious art as records of contact. Archaeologists reject the reading, noting that it discounts the abilities of the cultures that built the monuments. It is the root of the Anunnaki, Sirian and bird-headed 'Avian' archetypes.
- Anunnaki
Mesopotamian deities recast by Sitchin as genetic engineers from a hidden planet.
In Sumerian and Akkadian texts the Anunnaki are a group of gods. Zecharia Sitchin's books claim they were visitors from a planet he called Nibiru who created humans as workers. Assyriologists say his translations are wrong. The claim is nonetheless one of the most widespread ancient-astronaut stories.
- Area 51
A secret US Air Force test site in Nevada, tied by rumour to recovered craft.
The base at Groom Lake tested the U-2 and other classified aircraft, which explains many sightings in the area. Its link to alien craft rests mainly on Bob Lazar's 1989 television claims, which have never been verified. The CIA acknowledged the base's existence in 2013.
- Bedroom visitor
A being reported at the bedside on waking, often unable to move.
Bedroom visitations are the most common form of contact report, and they closely match the medical description of sleep paralysis with hypnopompic hallucination. Whitley Strieber's Communion begins with one. The 'Hat Man' and shadow-people reports belong to the same family of experiences.
- Black triangle
A large, silent, dark triangular craft with lights at the corners.
Triangles dominated reports from the late 1980s onward, notably the Belgian wave of 1989–1990 and the Phoenix Lights of 1997. Sceptics point to the F-117 and B-2 stealth aircraft, which entered service in the same years, and to aircraft flying in formation.
- Cattle mutilation
Livestock found dead with tissue removed, blamed by some on aliens.
Reports peaked in the American West in the 1970s. An FBI investigation and veterinary studies attributed the 'surgical' wounds to predators and scavengers acting on a bloated carcass. The theme survives in Reptilian and Grey lore as evidence of harvesting.
- Channelling
Receiving messages from a non-human intelligence while in a trance state.
Most of the 'galactic' species in the Atlas, including the Pleiadians, Arcturians, Lyrans and Andromedans, are known only through channelled books and sessions rather than sightings. The Atlas labels them speculative or channelled for that reason.
- Close encounter
J. Allen Hynek's scale for how near a witness came to the phenomenon.
Hynek's 1972 book defined three kinds: a sighting within about 500 feet (first kind), physical effects such as burned ground or a stalled engine (second kind), and visible occupants (third kind). Later writers added abduction (fourth kind) and human-initiated contact (fifth kind). Steven Spielberg's 1977 film made the phrase universal.
- Condon Report
The 1968 University of Colorado study that led the Air Force to close Blue Book.
Led by physicist Edward Condon and funded by the Air Force, the study concluded that further investigation would not advance science. Critics noted that around a third of its own cases remained unexplained and that Condon had voiced his conclusion early. It ended official public investigation for fifty years.
- Contactee
A person who claims friendly, repeated contact with visitors, usually with a message.
The contactee movement began with George Adamski in 1952 and flourished through the 1950s. Contactees described beautiful, human-looking visitors from Venus or the Pleiades with warnings about nuclear weapons. The Nordic archetype and much of the later channelling literature descend from it.
- Crop circle
Patterns flattened into fields, mostly in southern England, from the late 1970s.
In 1991 two men, Doug Bower and Dave Chorley, demonstrated that they had made many of the early circles with planks and rope. Elaborate formations continue to appear, made by artists, and remain a fixture of contact folklore.
- Disclosure
The hoped-for official admission that governments hold proof of non-human visitors.
The term describes a movement rather than an event. Its recent high points were the 2017 Times story, the 2021 ODNI report and the 2023 congressional testimony of David Grusch. AARO's 2024 review stated that it had found no such proof.
- Drake equation
Frank Drake's 1961 formula for estimating how many communicating civilisations exist.
The equation multiplies the rate of star formation by the fractions of stars with planets, habitable planets, life, intelligence and technology, and the length of time such a civilisation transmits. Most of its terms are unknown, so it is a framework for discussion rather than a prediction.
- EBE
Extraterrestrial Biological Entity, US intelligence slang adopted by the lore.
The abbreviation appears in the disputed Majestic 12 papers and in the Project Serpo story, where 'Ebens' are said to be visitors from Zeta Reticuli who hosted a human exchange team. No document containing the term has been authenticated.
- Experiencer
A neutral word for someone who reports contact, preferred by many to 'abductee'.
Used by researchers such as John Mack and by support groups, it describes the person without judging the cause of the experience. The Atlas uses 'witness' or 'experiencer' when summarising accounts.
- Extraterrestrial hypothesis
The view that some UFOs are craft from other planets.
Abbreviated ETH, it was the default explanation in the field from the 1950s and remains the most popular. Rival views include the psychosocial hypothesis, which treats reports as cultural and psychological, and the interdimensional hypothesis of Jacques Vallée and John Keel.
- Fermi paradox
If the galaxy should be full of civilisations, why is there no clear sign of them?
Attributed to a 1950 lunch-table remark by physicist Enrico Fermi. Proposed answers range from the rarity of life to a 'great filter' that ends civilisations, to the idea that they are here and undetected. Contact believers cite the last; astronomers generally do not.
- Flap
A cluster of sightings in one region over days or weeks.
Ufologists' word for a wave. Famous flaps include Washington, D.C. in July 1952, the Belgian wave of 1989–1990 and the Hudson Valley sightings of the 1980s. Flaps are shaped by media coverage, which prompts more people to look up and report.
- Flying saucer
The 1947 press term for a disc-shaped craft, coined after Kenneth Arnold's sighting.
Arnold described crescent-shaped objects that moved 'like a saucer skipped across water'; a reporter turned that into 'flying saucer' and the shape stuck. Discs dominated reports for three decades and remain the icon of the subject.
- Foo fighters
Glowing balls of light reported by Second World War pilots.
Allied aircrews over Europe and the Pacific reported lights that paced their aircraft. Explanations include St Elmo's fire, ball lightning and misperception. The reports predate the flying saucer era and are often cited as evidence that the phenomenon is older than 1947.
- Galactic Federation
A supposed alliance of benevolent species, known through channelled sources.
Also 'Galactic Federation of Light'. The idea of a council of advanced races overseeing Earth runs through the Pleiadian, Arcturian and Andromedan literature and through science fiction from Star Trek onward. It has no evidential basis and is labelled speculative throughout the Atlas.
- Grey
The small, large-eyed, grey-skinned being of most abduction accounts since 1961.
Described by the Hills, fixed by the cover of Communion in 1987 and reproduced across film and television, the Grey is the default alien of modern culture. Reports describe a height of three to five feet, a large head, black almond eyes and a small mouth. Sceptics note that the image's spread tracks its media exposure.
- Hybrid
A supposed child of human and alien parents, central to later abduction narratives.
Budd Hopkins's Intruders (1987) and David Jacobs's The Threat (1998) argued that abductions serve a breeding programme. The Villas Boas case of 1957 is the earliest claim of the kind. There is no physical evidence of any such child.
- Hynek classification
The system astronomer J. Allen Hynek devised to sort UFO reports.
Hynek was the Air Force's scientific consultant for Project Blue Book and grew from sceptic to advocate of serious study. His scheme divides distant sightings into nocturnal lights, daylight discs and radar-visual cases, and near ones into close encounters of the first, second and third kind.
- Hypnotic regression
Using hypnosis to recover memories of an encounter, a disputed method.
Regression produced the Hill, Allagash, Zanfretta and Andreasson narratives, among others. Memory researchers have shown that hypnosis increases confidence without increasing accuracy and can create detailed false memories through suggestion. Most of the abduction record depends on it.
- ʻOumuamua
The first known interstellar object to pass through the solar system, in 2017.
Its elongated shape and slight non-gravitational acceleration led Harvard astronomer Avi Loeb to suggest it could be an artificial probe. Most astronomers attribute the acceleration to outgassing from a natural body. It left before it could be studied closely.
- Implant
A small object said to have been placed in an abductee's body.
Several experiencers have had objects removed surgically, most famously by Dr Roger Leir in the 1990s. Analyses have found ordinary materials such as glass, metal fragments and calcified tissue. No implant has shown non-terrestrial composition or manufacture.
- Interdimensional hypothesis
The view that the phenomenon comes from another reality rather than another planet.
Jacques Vallée argued in Passport to Magonia (1969) that fairy lore, religious visions and UFO reports are one phenomenon wearing the costume of each age. John Keel reached a similar view in The Mothman Prophecies. The Avalonian and Shadow archetypes in the Atlas draw on it.
- Little green men
The comic stock alien of the 1950s, wrongly tied to the Kelly-Hopkinsville case.
The phrase was in print before 1955, but newspaper coverage of the Kelly farmhouse siege, whose witnesses actually described silver creatures, attached it to that case for good. It is now used mostly with irony.
- Magonia
A cloud-realm of medieval French legend, adopted by Vallée as a name for the phenomenon.
A ninth-century text by Agobard of Lyon describes people who believed ships sailed through the clouds from a land called Magonia. Jacques Vallée used the name for his argument that UFO lore continues an ancient pattern of otherworldly visitors.
- Majestic 12
A supposed secret committee formed in 1947 to manage recovered craft; the documents are disputed.
Papers naming a twelve-member group of scientists and officials surfaced in 1984 on undeveloped film sent to a researcher. The FBI and most document examiners consider them forgeries; a few researchers still defend them. They shaped the crash-retrieval mythology around Roswell.
- Men in Black
Dark-suited strangers who are said to visit witnesses and warn them to stay silent.
The story began with Albert Bender in 1953 and was developed by Gray Barker and John Keel. Descriptions of odd, pale, awkward men have been read as government agents, as hoaxers and as part of the phenomenon itself. The 1997 film turned them into comedy.
- Missing time
A gap of hours a witness cannot account for, taken as a sign of abduction.
Coined as a title by Budd Hopkins in 1981 and first noted in the Hill case, where a journey took two hours longer than expected. Psychologists observe that people routinely misjudge elapsed time on long night drives and that the 'gap' is often reconstructed afterward.
- Nordic
The tall, fair, human-looking visitor of contactee literature.
Named for the Scandinavian look described by Adamski and later contactees. Nordics are presented as benevolent, spiritual and concerned about Earth's future. The archetype is easy to trace to 1950s ideals and has been criticised for its racial coding.
- Nuts-and-bolts
The wing of ufology that treats UFOs as physical machines with occupants.
The term distinguishes researchers focused on hardware, radar and crash retrievals from those who study the experience as psychological or paranormal. Stanton Friedman was its best-known advocate.
- Orb
A ball of light, the most common shape in modern sighting reports.
Orbs range from distant lights to the glowing sphere of the Allagash case. They overlap with lanterns, drones, satellites, planets and ball lightning, and in photographs with dust caught by a flash.
- Panspermia
The hypothesis that life spreads between worlds on rocks, dust or deliberately.
Natural panspermia is a serious if unproven scientific idea. 'Directed panspermia', proposed by Francis Crick and Leslie Orgel in 1973, imagines an earlier civilisation seeding life on purpose. It appears in ancient-astronaut and Anunnaki lore as an origin story for humans.
- Project Blue Book
The US Air Force's public UFO investigation, 1952–1969.
Blue Book logged 12,618 reports and left 701 unidentified. It followed Project Sign (1948) and Project Grudge (1949) and closed after the Condon Report. Its files are declassified and searchable, and remain the largest official case archive.
- Radar-visual case
A sighting confirmed at the same time by radar and by eye.
Hynek considered these the strongest category of report. The Washington 1952 flap, the Tehran 1976 jet chase and the Belgian wave all involved radar tracks, though each has proposed explanations involving weather, equipment or misread returns.
- Reptilian
A lizard-like humanoid, from pulp fiction to David Icke's conspiracy theory.
Serpent-men appear in Robert E. Howard's 1929 story The Shadow Kingdom and in the 1983 series V. David Icke's claim that shape-shifting reptilians control world affairs dates from the 1990s and has been widely condemned for echoing antisemitic conspiracy tropes. The Atlas records the archetype and the criticism.
- Roswell
The 1947 New Mexico debris find that became the archetypal crash-retrieval story.
The Air Force's 1994 and 1997 reports identified the debris as a Project Mogul balloon train and the 'bodies' of later accounts as crash-test dummies from 1950s parachute tests. The story revived in 1978 through interviews with Major Jesse Marcel and has grown since.
- Screen memory
An ordinary image, such as an owl or deer, said to mask a memory of a being.
Borrowed from Freud, the term is used by abduction researchers to explain why witnesses remember animals with large eyes at the moment of contact. Sceptics reverse the logic: the witness saw an owl, and the alien was added later.
- SETI
The Search for Extraterrestrial Intelligence, listening for signals since 1960.
SETI uses radio and optical telescopes to look for artificial signals. The 1977 'Wow!' signal remains its most famous unexplained detection. SETI scientists generally regard UFO reports as a separate matter with a different standard of evidence.
- Shadow people
Dark, featureless figures seen at the edge of vision or at the bedside.
Reports grew after a 2001 radio call-in and spread online. The 'Hat Man', a tall silhouette in a brimmed hat, is the best-known form. Sleep paralysis is the usual explanation. The Atlas files them under non-physical entities.
- Sleep paralysis
Waking while the body is still paralysed, often with a felt presence and hallucinations.
Experienced by a large share of people at least once. The classic episode includes pressure on the chest, a sense of an intruder, and vivid figures at the bedside. It is the leading scientific explanation for bedroom-visitor and many abduction reports, and matches older 'old hag' and incubus folklore.
- Star People
Sky beings of many Indigenous American traditions, respected as ancestors and teachers.
Stories of relatives from the stars belong to the oral traditions of many nations and predate the UFO era. Ardy Sixkiller Clarke, a Cherokee-Choctaw scholar, collected modern accounts in Encounters with Star People (2012). The Atlas entry is written with those traditions' own framing.
- Starseed
A person who believes their soul originated on another world.
A New Age identity that grew from the channelling literature of the 1980s and spread widely online. Starseeds often identify with a specific home such as the Pleiades, Sirius or Arcturus. It is a belief about the self rather than a sighting claim.
- Tall White
Very tall, pale beings described by Charles Hall at Nellis Air Force Base.
Hall, a former Air Force weather observer, wrote in Millennial Hospitality (2002) that Tall Whites lived at a Nevada range in the 1960s under a government arrangement. No one has corroborated the account. The type overlaps with the Nordic archetype.
- Tic Tac
The white, wingless object reported by Navy pilots off California in 2004.
Named for its shape by pilot David Fravor of the USS Nimitz carrier group. The FLIR1 video and the pilots' testimony became public in 2017 and were confirmed as genuine Navy footage by the Pentagon in 2020. Its identity remains officially unresolved.
- Trace case
A sighting that leaves physical marks: burns, depressions, radiation, stalled engines.
Hynek's close encounter of the second kind. Socorro in 1964, with its burned ground and landing impressions, is the best-known American example. Traces are evidence that something happened, not proof of what.
- UAP
Unidentified anomalous phenomena, the official term that replaced UFO.
First 'unidentified aerial phenomena', broadened in 2022 to 'anomalous' to include objects in space and under water. The change was meant to remove the stigma of 'UFO' and reflect the fact that 'unidentified' does not mean 'alien'.
- UFO
Unidentified flying object, a term coined by the US Air Force in 1953.
Captain Edward Ruppelt of Project Blue Book introduced it to replace 'flying saucer'. By definition a UFO is anything in the sky the observer cannot identify; the great majority turn out to be aircraft, balloons, satellites, planets and birds. Popular use makes it a synonym for alien craft.
- Ufology
The study of UFO reports, mostly outside academia.
Practised by civilian groups such as MUFON, NICAP and CUFOS, by individual investigators and, since 2017, by a renewed official effort. It has no agreed method and spans careful case investigation, contactee belief and conspiracy theory.
- Ummo
A supposed planet whose inhabitants sent thousands of letters to Spain from the 1960s.
The Ummo letters described a scientific civilisation in dense detail and were long treated by some as genuine. A Spanish psychologist, José Luis Jordán Peña, later said he had written them as an experiment. The Ummite entry records the affair.
- Vril
A fictional energy from an 1871 novel, later woven into Nazi-UFO myths.
Edward Bulwer-Lytton's The Coming Race imagined a subterranean people powered by Vril. Post-war writers invented a 'Vril Society' in contact with Aldebaran that built flying discs for the Third Reich. Historians have found no evidence such a society existed.
- Walk-in
A soul that is said to replace another in a living body, often from another world.
Popularised by Ruth Montgomery's Strangers Among Us (1979). The idea belongs to New Age and channelling belief rather than to sighting reports, and it overlaps with the starseed identity.
- Wow! signal
A strong, unexplained radio signal detected by Ohio State's Big Ear telescope in 1977.
Astronomer Jerry Ehman circled the printout and wrote 'Wow!' beside it. The 72-second signal matched what an artificial narrowband transmission might look like and was never detected again. Natural explanations, including a hydrogen cloud, have been proposed.
- Zeta Reticuli
A binary star system 39 light-years away, named as the Greys' home by the Hill star map.
Marjorie Fish's 1974 interpretation of Betty Hill's sketched star map placed the beings' origin at Zeta Reticuli. Later star catalogues undermined the match, and Carl Sagan showed random patterns fit as well. The name nonetheless became fixed in Grey lore and in the Serpo story.
For the conventional explanations behind these terms, read What people actually saw. XenoAtlas documents extraterrestrial concepts appearing in mythology, contactee literature, popular culture, speculative accounts, and related sources. Inclusion does not constitute scientific verification.