plural UFO's or UFOs /ˌjuːˌɛfˈoʊz/ plural UFO's or UFOs /ˌjuːˌɛfˈoʊz/ Learner's definition of UFO
[count]
: a flying object in the sky that some people believe could be a spaceship from another planet不明飞行物 ◊ UFO is as an abbreviation of “unidentified flying object.”*UFO是unidentified flying object的缩略词。