retain vs retention

retain is not a noun while retention is a noun.

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

retain (noun)	retention (noun)
	the act of retaining something
	the power of retaining liquid
	the power of retaining and recalling past experience

retain (verb)	retention (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