Fighter (noun)

1. A person who fights, especially a soldier or warrior.
2. A person who fights for a cause or principle.

Origin:

Late middle english: from old french fichier "to attack", from fiche "point of a weapon", from medieval latin ficcare, from latin fixus "fixed".

Examples:

1. The fighters were well trained.
2. He was a fighter pilot in the war.
3. The boxer was a fierce fighter.
4. She was a fighter for women's rights.
5. The civil rights movement had many fighters.