Adiabatic

[Sarah]

Not giving out or receiving heat.-- Adically, adv. Adiabatic line or curve, a curveexhibiting the variations of pressure and volume of a fluid when itexpands without either receiving or giving out heat. Rankine.

[Sarah]

Occurring without loss or gain of heat.

[Kai]

Adiabatic in Weather Forecast. A change in temperature of a mass of air caused by changes in pressure without any gain or loss of heat from its surroundings.

[Magaret]

Relating to or denoting a process or condition in which heat does not enter or leave the system concerned.