flapping.

that flaps or flap

flapping sails

An instance where one, or something, flaps.

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.

The situation where a resource, a network destination, etc., is advertised as being available and then unavailable (or available by different routes) in rapid succession.

The unlicensed racing of horses or greyhounds.

present participle and gerund of flap