belligerent vs boxer

belligerent and boxer both are nouns.

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

As nouns, boxer is a hyponym of belligerent; that is, boxer is a word with a more specific, narrower meaning than belligerent:

belligerent (noun)	boxer (noun)
someone who fights (or is fighting)	a breed of stocky medium-sized short-haired dog with a brindled coat and square-jawed muzzle developed in Germany
	someone who fights with his fists for sport
	a workman employed to pack things into containers

belligerent (adjective)	boxer (adjective)
characteristic of an enemy or one eager to fight
engaged in war