rehearsal vs rehearse

rehearsal is a noun but rehearse is not a noun.

Word	Noun	Adjective	Verb	Adverb
rehearsal	Yes	No	No	No
rehearse	No	No	Yes	No

rehearsal (noun)	rehearse (noun)
(psychology) a form of practice; repetition of information (silently or aloud) in order to keep it in short-term memory
a practice session in preparation for a public performance (as of a play or speech or concert)

rehearsal (verb)	rehearse (verb)
	engage in a rehearsal (of)