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

Godzilla’s foe here, a giant living UFO that absorbs information and eventually attempts to absorb Godzilla’s own regenerative powers, is interesting in theory but ends up being one of the worst monsters in the series. —James Grebey, Vulture, 9 Jan. 2026

According to a new study, Rhode Island is the 23rd best state to spot a UFO. —Will Richmond, The Providence Journal, 9 Jan. 2026

Guo has also directed several award-winning films including She, A Chinese and UFO in Her Eyes, and has had film retrospectives around the world. —Literary Hub, 6 Jan. 2026

Spielberg’s next film as a director — opening in June — is a UFO epic, being touted as a return to one of his classic subjects. —Christopher Borrelli, Chicago Tribune, 1 Jan. 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