retort vs repay

retort is a noun but repay is not a noun.

Word	Noun	Adjective	Verb	Adverb
retort	Yes	No	Yes	No
repay	No	No	Yes	No

As verbs, retort and repay are synonyms defined as:

Other synonyms of retort include come back, rejoin, return, riposte.

retort (noun)	repay (noun)
a vessel where substances are distilled or decomposed by heat
a quick reply to a question or remark (especially a witty or critical one)

retort (verb)	repay (verb)
answer back	answer back
	pay back
	make repayment for or return something
	act or give recompense in recognition of someone's behavior or actions