From Longman Dictionary of Contemporary Englishbelly flopˈbelly flop noun [countable] DSSa way of jumping into water, in which the front of your body falls flat against the surface of the water —bellyflop verb [intransitive]
Examples from the Corpus
belly flop• The rest of the league has been waiting for a belly flop, but the Giants' cagey right-hander refuses to wilt. 