endorse vs endorser

endorse is not a noun while endorser is a noun.

Word	Noun	Adjective	Verb	Adverb
endorse	No	No	Yes	No
endorser	Yes	No	No	No

endorse (noun)	endorser (noun)
	someone who expresses strong approval
	a person who transfers his ownership interest in something by signing a check or negotiable security

endorse (verb)	endorser (verb)
sign as evidence of legal transfer
be behind; approve of
guarantee as meeting a certain standard
give support or one's approval to