coolant

Etymology

cool + -ant

noun

1. A medium, usually fluid, used to draw heat from an object.
   Coolant is used in car engines and industrial processes, where excess heat could cause machine damage.
   Anti-freeze has not been found necessary, even in the most severe conditions, since the water is drained out if a locomotive spends any appreciable time out of service and in normal working conditions the coolant is always warm. 1962 October, M. J. Wilson, “Three years of dieselisation at Devons Road depot”, in Modern Railways, page 264