valve rocker vs lever

valve rocker and lever both are nouns.

Word	Noun	Adjective	Verb	Adverb
valve rocker	Yes	No	No	No
lever	Yes	No	Yes	No

As nouns, lever is a hypernym of valve rocker; that is, lever is a word with a broader meaning than valve rocker:

valve rocker: a lever pivoted at the center; used especially to push a valve down in an internal-combustion engine
lever: a rigid bar pivoted about a fulcrum

valve rocker (noun)	lever (noun)
a lever pivoted at the center; used especially to push a valve down in an internal-combustion engine	a rigid bar pivoted about a fulcrum
	a flat metal tumbler in a lever lock
	a simple machine that gives a mechanical advantage when given a fulcrum

valve rocker (verb)	lever (verb)
	to move or force, especially in an effort to get something open