UFO (Unidentified Flying Object)

UFO / noun (plural UFOs)

an object in the sky that you don’t recognize;

some people think it might be a space vehicle from another world;

a strange object that some people think they’ve seen in the sky and that may come from another planet.

UFO is the short for ‘unidentified flying object’.


In the Encyclopedia of Wikipedia has come that:

An unidentified flying object, or UFO, is any real or apparent flying object which cannot be identified by the observer and which remains unidentified after investigation. In popular culture, UFO is often used to refer to any hypothetical, or unproven, alien spacecraft. The term flying saucer is also sometimes used.

Reference:
1) Longman Basic Dictionary of American English
2)Oxford Elementary Learner’s Dictionary