repay vs riposte

repay is not a noun while riposte is a noun.

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

As verbs, repay and riposte are synonyms defined as:

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

repay (noun)	riposte (noun)
	(fencing) a counterattack made immediately after successfully parrying the opponents lunge
	a quick reply to a question or remark (especially a witty or critical one)

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