unidentified flying object
- A flying or apparently flying object of an unknown nature, especially one suspected to have been sent by extraterrestrial beings.
- A flying saucer.
(plural unidentified flying objects)
- Anything not readily explainable appearing to move through or be suspended in the air, primarily used to refer to objects that seem to be at least of small familiar aircraft size. Abbreviated UFO.
- The lights seen over the city last night, originally termed unidentified flying objects, turned out to be spotlights from a car dealership reflecting on low clouds.
- (colloquial) An alien spacecraft. More commonly called a UFO.
The phrase is usually attributed to Edward J. Ruppelt who coined it as a replacement of the terms flying saucer and flying disk.