From Longman Dictionary of Contemporary Englishflying saucerˌflying ˈsaucer noun [countable] TTSa large round spacecraft from somewhere else in space, that some people believe they have seen in the sky → UFO
Examples from the Corpus
flying saucer• He said, too, that he had been kidnapped by a flying saucer in 1967.• He would not raise his eyes to the sky, though he knew there was a flying saucer from Tralfamadore up there.• His flying saucer, however, is made of glass fibre and runs on compressed air.• On this particular occasion however, it is a nifty little flying saucer.• If you stare at the flying saucer long enough it begins to vibrate. 