[ koo-luhnt ]

  1. a substance, usually a liquid or a gas, used to reduce the temperature of a system below a specified value by conducting away the heat produced in the operation of the system, as the liquid in an automobilecooling system or the fluid that removes heat from the core of a nuclear reactor.

  2. a lubricant that dissipates the heat caused by friction.

Origin of coolant

First recorded in 1925–30; cool + -ant

Words Nearby coolant Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use coolant in a sentence

British Dictionary definitions for coolant


/ (ˈkuːlənt) /

  1. a fluid used to cool a system or to transfer heat from one part of it to another

  2. a liquid, such as an emulsion of oil, water, and soft soap, used to lubricate and cool the workpiece and cutting tool during machining

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012