An outfall fitted with a metal flap so that floodwater will not back up

Pronunciation spelling of flapping.

plural of fire flapper

plural of flapped outfall

plural of flapping hinge

Reminiscent of a flapper (unconventional young woman of the 1920s).

present participle of flip-flap

simple past tense and past participle of flip-flap

(historical) A mechanical display board, used at railway stations etc., having the text characters on individual flaps that can be rotated to form different messages.

plural of flapper board