combatant vs belligerent

combatant and belligerent both are nouns.

Word	Noun	Adjective	Verb	Adverb
combatant	Yes	Yes	No	No
belligerent	Yes	Yes	No	No

As nouns, combatant and belligerent are synonyms defined as:

Other synonyms of combatant include battler, fighter, scrapper.

combatant (noun)	belligerent (noun)
someone who fights (or is fighting)	someone who fights (or is fighting)

combatant (adjective)	belligerent (adjective)
engaging in or ready for combat	characteristic of an enemy or one eager to fight
	engaged in war