n. (Mach.) 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. [ 1913 Webster ]

. (Mech.) A rod carrying a tappet or tappets, as one for closing the valves in a Cornish pumping engine. [ Webster 1913 Suppl. ]