Butt flap, a separately removable part of underwear (un)covering the buttocks

Flap, any hinged plate often used as a cover or a simple one-way valve

Flapper, a woman who wore a certain style of clothes in the 1920s

Flap consonant, a sound produced by brief contact between the tongue and the roof of the mouth

Free flap, a surgical transfer of vascularised tissue

Sluice or flap gate, a pressure driven water flow control device between a channel and other water body

Flap (aircraft), a hinged surface on the trailing edge of an airplane wing

Intervocalic alveolar flapping, a process by which a /t/ phoneme] before an unstressed vowel is pronounced as a flap consonant

Cat flap, a hinged flap that allows a cat to enter or leave a room or building

5-lipoxygenase activating protein (FLAP)

Brouhaha, a general state of social agitation

Route flapping, when a router alternately advertises a destination network first via one route then another

Flap (Little Nemo), a minor character from Little Nemo: Adventures in Slumberland