UFO

American  

[yoo-ef-oh, yoo-foh] / ˈyuˈɛfˈoʊ, ˈyu foʊ /

abbreviation

plural

UFO's, UFOs

1. unidentified flying object: any unexplained moving object observed in the sky, especially one assumed by some observers to be of extraterrestrial origin.

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UFO British  

/ ˈjuːfəʊ /

abbreviation

1. unidentified flying object

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UFO ¹ Cultural  

1. The abbreviation for u nidentified f lying o bject. Sometimes referred to colloquially as “flying saucers.” Most UFO sightings have prosaic explanations; there is no hard evidence that extraterrestrial beings are visiting Earth.

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UFO ² Cultural  

1. An abbreviation for “U nidentified F lying O bject.” Often described as “flying saucers,” some UFOs are believed to come from other planets or galaxies and thus support the idea that human beings are not the only form of intelligent life in the universe. Few scientists agree.

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Usage

See UAP.

Etymology

Origin of UFO

First recorded 1950–55

Example Sentences

UFO cabin crew also walked out on Friday at both Lufthansa and CityLine in a dispute over working conditions.

From Barron's • Apr. 13, 2026

Brazil’s UFO capital marks 30 years since alleged alien encounter.

From MarketWatch • Mar. 24, 2026

Perhaps the most likely reveal of any new probe into Washington’s UFO files will be that many people at the Pentagon are just as fascinated by the prospect of aliens as the rest of America.

From The Wall Street Journal • Feb. 22, 2026

I liked it better when this was simply known as “Untitled Steven Spielberg UFO movie.”

From Los Angeles Times • Jan. 1, 2026

Julia was standing with them, trying again to convince Jay about her stupid tinfoil UFO and how it was going to fly up and down the street on a stupid invisible wire.

From "When You Reach Me" by Rebecca Stead