1. people who fight in wars, battles, or physical conflicts
2. people who participate in boxing or other combat sports
3. military aircraft designed for attacking enemy aircraft

Examples

• The brave fighters defended their homeland against invasion.
• Two professional fighters will compete in tonight’s boxing match.
• The air force deployed fighter jets to patrol the border.
• She admired the civil rights fighters who changed history.
• The cancer fighters in the support group encouraged each other.
• Enemy fighters were spotted approaching from the east.
• The MMA fighters trained for months before the championship.