Inside the Universes

'coolant.n.01'

[coolant.n.01] as in: a fluid agent (gas or liquid) that produces cooling; especially one used to cool a system by transferring heat away from one part to another

Examples:
he added more coolant to the car's radiator
the atomic reactor used a gas coolant
lathe operators use an emulsion of oil and water as a coolant for the cutting tool