Definition of "flapping"
flapping
/ˈflæpɪŋ/
noun
countable and uncountable, plural flappings
(phonology) A phonological process found in many dialects of English, especially American English and Canadian English, by which intervocalic /t/ and /d/ surface as the alveolar flap /ɾ/ before an unstressed syllable, so that words such as "metal" and "medal" are pronounced similarly or identically.
(uncountable) The unlicensed racing of horses or greyhounds.