flap valve

Webster's Dictionary (GCIDE)

Flap \Flap\, n. [OE. flappe, flap, blow, bly-flap; cf. D. flap, and E. flap, v.] Anything broad and limber that hangs loose, or that is attached by one side or end and is easily moved; as, the flap of a garment. [1913 Webster]

A cartilaginous flap upon the opening of the larynx. --Sir T. Browne. [1913 Webster]

2.A hinged leaf, as of a table or shutter. [1913 Webster]

3.The motion of anything broad and loose, or a stroke or sound made with it; as, the flap of a sail or of a wing. [1913 Webster]

4.pl. (Far.) A disease in the lips of horses. [1913 Webster]

5.(Aeronautics) a movable part of an airplane wing, used to increase lift or drag, especially when taking off or landing. used often in the plural. [WordNet 1.5]

Flap tile, a tile with a bent up portion, to turn a corner or catch a drip.

Flap valve (Mech.), a valve which opens and shuts upon one hinged side; a clack valve. [1913 Webster]