1. a device that produces heat to warm a room, building, or water
2. a gun or pistol
Usage: slang

Examples

• The space heater kept the small room warm all winter.
• We need to replace the water heater in the basement.
• Turn on the car heater; it’s freezing outside.
• The electric heater uses too much energy.
• Our old gas heater finally broke down.
• The portable heater is perfect for the garage.