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UFO

Look, up in the sky! It's a bird! It's a plane! It's...a UFO. A UFO, or unidentified flying object, is anything seen in the sky that can't be identified.

You may think of UFOs as the product of overactive imaginations and conspiracy theories, but the term itself was coined by the U.S. Air Force in 1953. It's an official way to categorize sightings that can't be explained scientifically. Most UFOs, however, do turn out to either have simple explanations or to be hoaxes. But if you believe you see a flying saucer or an alien craft, go ahead and call it a UFO.

Definitions of UFO
  1. noun
    an (apparently) flying object whose nature is unknown; especially those considered to have extraterrestrial origins
    synonyms: flying saucer, unidentified flying object
    see moresee less
    type of:
    apparition, fantasm, phantasm, phantasma, phantom, shadow
    something existing in perception only
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