clapper : Idioms & Phrases
Clapper rail
(Zoöl.) , an Americam species of rail (Rallus scepitans ).
Webster 1913
clapper valve
-
noun a simple valve with a hinge on one side; allows fluid to flow in only one direction
clack valve; clack.
WordNet
Shoulder clapper
- one who claps another on the shoulder, or who uses great familiarity. Obs. Shak.