the.com/unidentified flying object

means Something seen moving in the sky whose nature, origin, or identity cannot be determined at the time it's observed.

from Coined by the US Air Force in the early 1950s as a deliberately neutral, bureaucratic label — 'unidentified flying object' simply meant an aerial sighting investigators hadn't yet explained, with no claim about aliens or spacecraft baked in. The term (and its clipped cousin UFO) was popularized through official projects like Project Blue Book, but once it escaped into public imagination, it quickly came to mean one thing in everyday speech: extraterrestrial visitors, not the cautious 'we don't know yet' the military intended.