retain vs retentive

retain is not an adjective while retentive is an adjective.

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

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

retain (verb)	retentive (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