1) Assailant 2) Belligerent 3) Bludgeon man 4) Boxer 5) Bully 6) Champion 7) Competitor 8) Controversialist 9) Corrival 10) Disputant 11) Duelist 12) Fighter 13) French word used in English 14) Litigant 15) Military 16) Mosstrooper 17) Paladin 18) Polemic 19) Pugilist 20) Rebel 21) Rival 22) Rough 23) Soldier 1) Battler 2) Boxer 3) Brawler 4) Fencer 5) Fighter 6) Foe 7) Gladiator 8) Gladiatorial 9) Gouger 10) Grappler 11) Matman 12) Mauler 13) Pugilist 14) Pugilistic 15) Scrapper 16) Skirmisher 17) Soldier 18) Swordsman 19) Victor 20) Wrestler 
A combatant is a person who takes a direct part in the hostilities of an armed conflict. If a combatant follows the law of war, then he or she is considered a privileged combatant and upon capture, he or she will qualify as a prisoner of war under the Third Geneva Convention (GCIII). An unprivileged combatant is a person, such as a mercenary, who ...
• (n.) One who engages in combat. • (a.) Contending; disposed to contend.
Com'bat·ant adjective [ French combattant , present participle] Contending; disposed to contend. B. Jonson. 
In heraldry combatant describes two bearings in the position of fighting - set face to face, each rampant.
[adj] - engaging in or ready for combat 2. [n] - someone who fights (or is fighting)
combatant 1. Anyone who attempts to destroy or to control something considered to be harmful; such as, measures to combat pollution. 2. Someone who resists or opposes (beats or defeats) someone or something actively.
adjective engaging in or ready for combat
a nation engaged in active fighting with enemy forces. · a person or group that fights.