coolant definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
a substance, usually a fluid, used to remove heat, as from a nuclear reactor, an internal-combustion engine, molten metal, etc.
coolant definition by American Heritage Dictionary
An agent that produces cooling, especially a fluid that draws off heat by circulating through an engine or by bathing a mechanical part.