1. a liquid or gas used to remove heat from something, especially in engines or machinery

Examples

• The car’s engine overheated because it was low on coolant.
• The mechanic checked the coolant level in the radiator.
• Nuclear reactors use water as a coolant to prevent overheating.
• The computer’s cooling system circulates coolant through the processor.
• Always let the engine cool down before adding more coolant.
• The coolant leaked onto the garage floor, leaving a green puddle.