getting even vs paying back

getting even and paying back both are nouns.

Word	Noun	Adjective	Verb	Adverb
getting even	Yes	No	No	No
paying back	Yes	No	No	No

As nouns, getting even and paying back are synonyms defined as:

Other synonyms of getting even include return.

getting even (noun)	paying back (noun)
a reciprocal group action	a reciprocal group action