noun

a person or nation engaged in fighting during a war.

in the long Russo-Swedish conflict, both combatants endured terrible sacrifices

fighter,fighting man,fighting woman,soldier,serviceman,servicewoman,warrior,trooper

adjective

engaged in fighting during a war.

all the combatant armies went to war with machine guns

warring,at war,opposing,contending,belligerent,combating,fighting,battling,conflicting,clashing