rocker arm vs lever

rocker arm and lever both are nouns.

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

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

rocker arm: 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

rocker arm (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

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