From Longman Dictionary of Contemporary Englishflipperflip‧per /ˈflɪpə $ -ər/ noun [countable] 1 a flat part on the body of some large sea animals such as seals, that they use for swimming2 
a large flat rubber shoe that you wear to help you swim faster
a large flat rubber shoe that you wear to help you swim fasterExamples from the Corpus
flipper• He held his spear gun out in front of him with the safety off and used his flippers to keep facing the fish.• A dolphin drew alongside, and by counter-opposing its flippers, barrel-rolled right in front of his mask.• All eventually disappeared except the rorqual's flippers and teeth, for which the Marine Biological Laboratory had put in a request.• A boy born with flippers, which never ceased twitching.FlipperFlipper a US television programme from the 1960s in which a family become friends with a dolphin that they call ‘Flipper’ 