1. Physics.a method of cooling a gas, utilizing the rapid expansion of a compressed portion of the gas, before it becomes liquid, to cool the remainder.
2. Rocketry.the cooling of a reaction engine by circulating around it the liquid propellant prior to its use in the combustion chamber of the engine, the heat energy absorbed by the propellant contributing to the total thrust of the exhaust.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.