fistfight vs combat

fistfight and combat both are nouns.

Word	Noun	Adjective	Verb	Adverb
fistfight	Yes	No	Yes	No
combat	Yes	No	Yes	No

As nouns, combat is a hypernym of fistfight; that is, combat is a word with a broader meaning than fistfight:

Other hypernyms of fistfight include fight, fighting, scrap.

fistfight (noun)	combat (noun)
a fight with bare fists	an engagement fought between two military forces
	the act of fighting; any contest or struggle

fistfight (verb)	combat (verb)
fight with the fists	battle or contend against in or as if in a battle