belligerent vs combatant

belligerent and combatant both are nouns.

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

As nouns, belligerent and combatant are synonyms defined as:

Other synonyms of belligerent include battler, fighter, scrapper.

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

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