retentive vs retain

retentive is an adjective but retain is not an adjective.

Word	Noun	Adjective	Verb	Adverb
retentive	No	Yes	No	No
retain	No	No	Yes	No

retentive (adjective)	retain (adjective)
good at remembering
having the capacity to retain something
having the power, capacity, or quality of retaining water

retentive (verb)	retain (verb)
	keep in one's mind
	secure and keep for possible future use or application
	allow to remain in a place or position or maintain a property or feature
	hold back within