UFO

noun

ˌyü-(ˌ)ef-ˈō 

ˈyü-(ˌ)fō

plural UFO's or UFOs ˌyü-(ˌ)ef-ˈōz 

ˈyü-(ˌ)fōz

: a mysterious flying object in the sky that is sometimes assumed to be a spaceship from another planet : unidentified flying object

"All right." The President sighed. "Is there anybody around this table who thinks UFOs and this signal from Vega have anything to do with each other?"

—Carl Sagan

In 1966, the first UFO "abduction" was described in journalist John G. Fuller's book The Interrupted Journey.

—Keay Davidson

called also UAP, unidentified aerial phenomenon, unidentified anomalous phenomenon

Examples of UFO in a Sentence

Recent Examples on the Web

In the presentation, Ruppelt revealed that roughly 20% of the 800 UFO reports the Air Force had investigated were still a mystery. — Stefan Becket, CBS News, 18 Sep. 2026

That poll found that about half of Americans, 49 percent, think all Unidentified Flying Object (UFO) sightings can be explained by human activity on Earth or natural phenomena. — Leonard David, Space.com, 14 Sep. 2026

Maybe your house will be alien and UFO themed with a landing pad in the yard. — Kaitlyn Keegan, Hartford Courant, 14 Sep. 2026

David Cook, Newmarket, England UFO’s ‘Rock Bottom’ Thanks again for another fun article. — George Varga, San Diego Union-Tribune, 6 Sep. 2026

Word History

Etymology

unidentified flying object

First Known Use

1952, in the meaning defined above

Rhymes for UFO

• acknow
• aglow
• ago
• airglow
• aloe
• altho
• although
• ammo
• backflow
• backhoe
• banjo
• barbeau

Kids Definition

UFO

noun

ˌyü-(ˌ)ef-ˈō 

plural UFO's or UFOs -ˈōz 

: an unidentified flying object

especially : flying saucer