[koo-luh
nt] 
| 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 automobile cooling system or the fluid that removes heat from the core of a nuclear reactor. |
| 2. | a lubricant that dissipates the heat caused by friction. |
| cool·ant (kōō'lənt) n. An agent that produces cooling, especially a fluid that draws off heat by circulating through an engine or by bathing a mechanical part. |