fellow vs couplet

fellow and couplet both are nouns.

Word	Noun	Adjective	Verb	Adverb
fellow	Yes	No	No	No
couplet	Yes	No	No	No

fellow (noun)	couplet (noun)
a boy or man	a stanza consisting of two successive lines of verse; usually rhymed
a man who is the lover of a man or woman	two items of the same kind
a friend who is frequently in the company of another
a person who is member of one's class or profession
an informal form of address for a man
a member of a learned society
one of a pair