UFO
noun [ C ] uk/ˌjuː.efˈəʊ/ us/ˌjuː.efˈoʊ/
不明飞行物，飞碟，幽浮（unidentified flying object的缩写）
abbreviation for unidentified flying object: an object seen in the sky that is thought to be a spacecraft from another planet
Several UFO sightings have been reported. 已接到了数起发现不明飞行物的报告。
Compare: flying saucer