n an (apparently) flying object whose nature is unknown; especially those considered to have extraterrestrial origins
不明飞行物, 飞碟
1. I saw a UFO in the sky last night.
我昨晚在天空中看到了一个飞碟。
2. Many people believe that UFOs are alien spaceships.
许多人相信飞碟是外星飞船。
3. The government released documents about UFO sightings.
政府发布了关于飞碟目击事件的文件。