unidentified aerial phenomenon
noun
plural unidentified aerial phenomena
: a mysterious flying object in the sky that is sometimes assumed to be a spaceship from another planet : uap
—used especially as an alternative to UFO or unidentified flying object
Unidentified aerial phenomena (UAP), formerly referred to as UFOs, in theory, could include alien spacecraft, but the two aren't synonymous. The Defense Department's All-Domain Anomaly Resolution Office (AARO) considers a UAP "anything in space, in the air, on land, in the sea or under the sea that can't be identified and might pose a threat to U.S. military installations or operations."—Urja Sinha et al.
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“Unidentified aerial phenomenon.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/unidentified%20aerial%20phenomenon. Accessed 8 Jul. 2026.
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