refund vs repay

refund is a noun but repay is not a noun.

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

As verbs, refund and repay are synonyms defined as:

Other synonyms of refund include give back, return.

refund (noun)	repay (noun)
the act of returning money received previously
money returned to a payer

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