noun
fighter
FY-ter/ˈfaɪtər/
A person engaged in combat against an opponent.
The fighter throws a punch toward the opposing boxer.

Etymology
Fight plus the agent ending names someone who engages in combat. The same role-based name was later applied to a fast military aircraft used for combat.
In context
fights are won not on fight night, but in the unseen hours when the body screams for relief and the fighter refuses to listen.
More examples
- Both fighters shake hands before the match begins.
- Enemy fighters retreat across the river after the battle.
- The injured fighter refuses to leave the ring.
Forms
fighter · fighters
fight verb — Engage in combat against an opponent.