The brief summary that often appears on the inside of a hardcover book's dust jacket.

(film) A failure in audio-video synchronization, so that an actor's lips move but no sound is heard.

(automotive) A small butterfly valve fitted to the intake manifold just before the cylinder head intake ports of many modern automotive diesel engines, and around which air can pass even when it is closed.

plural of swirl flap

A pet door.

A doggie door.

plural of flapped outfall

plural of flap gate

plural of flip-flap

(chiefly in plural) A publishing format of a paperback book with folded flyleaves, or either of the two flyleaves so folded.