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

Airline and ground personnel at Chicago’s O’Hare International Airport reported seeing a UFO hovering over the airport and then darting up, leaving a hole in the clouds. — Kori Rumore, Chicago Tribune, 7 Nov. 2026

The files were released as part of a federal initiative launched in May to make government records about UFO sightings and investigations publicly available. — Toria Sheffield, PEOPLE, 31 Oct. 2026

This award-winning concrete dome in the high desert is designed to look like a UFO, with soaring curved ceilings, plaster walls the color of the moon, and furniture carved from boulders. — Angela Tafoya, Vogue, 27 Oct. 2026

The top of the model depicts a spinning UFO floating above one of those iconic coniferous forests that dominated 90s sci-fi. — Ian Stokes, Space.com, 19 Oct. 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