Definitions for tappetˈtæp ɪt
Random House Webster's College Dictionary
a sliding rod that moves another machine part, as a valve, when intermittently struck by a cam.
Origin of tappet:
a lever that is moved in order to tap something else
A lever or projection which is moved by some other piece, as a cam, or intended to tap or touch something else, in order to produce change or regulate motion.
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