maintain vs maintainer

maintain is not a noun while maintainer is a noun.

Word	Noun	Adjective	Verb	Adverb
maintain	No	No	Yes	No
maintainer	Yes	No	No	No

maintain (noun)	maintainer (noun)
	someone who upholds or maintains

maintain (verb)	maintainer (verb)
stick to correctly or closely
state categorically
state or assert
support against an opponent
maintain by writing regular records
supply with necessities and support
keep in safety and protect from harm, decay, loss, or destruction
have and exercise
maintain for use and service
cause to continue in a certain state, position, or activity