improvise vs improvisation

improvise is not a noun while improvisation is a noun.

Word	Noun	Adjective	Verb	Adverb
improvise	No	No	Yes	No
improvisation	Yes	No	No	No

improvise (noun)	improvisation (noun)
	an unplanned expedient
	a performance given extempore without planning or preparation
	a creation spoken or written or composed extemporaneously (without prior preparation)

improvise (verb)	improvisation (verb)
perform without preparation
manage in a makeshift way; do with whatever is at hand