tappet

• POS: Noun
• HYPHEN: tap=pet

CIDE DICTIONARY

tappet, n. 

 A lever or projection moved by some other piece, as a cam, or intended to tap or touch something else, with a view to produce change or regulate motion.  G. Francis.  [1913 Webster]

Tappet motion, a valve motion worked by tappets from a reciprocating part, without an eccentric or cam, -- used in steam pumps, etc.

OXFORD DICTIONARY

tappet, n. a lever or projecting part used in machinery to give intermittent motion, often in conjunction with a cam.

Etymology

app. f. TAP(2) + -ET(1)