1. a person or thing that prevents something from happening
2. a rope or chain used to prevent a sail or boom from swinging
Usage: nautical

Examples

• The security system acts as a crime preventer.
• Regular exercise is an excellent disease preventer.
• The fire preventer sprayed foam on the burning building.
• Safety equipment serves as an accident preventer in the workplace.
• The sailor secured the preventer to keep the boom steady.
• Without the preventer, the sail could swing dangerously in strong winds.