The Collaborative International Dictionary of English v.0.48:

Adiabatic \Ad`i*a*bat"ic\, a. [Gr. 'adia`batos not passable; 'a
   priv. + dia` through + bai`nein to go.] (Physics)
   Not giving out or receiving heat. -- Ad`i*a*bat`ic*al*ly,
   adv.
   [Webster 1913 Suppl.]

   Note: The adiabatic expansion of carbon dioxide from a
         compressed container causes the temperature of the gas
         to decrease rapidly below its freezing point, resulting
         in the familiar carbon dioxide "snow" emitted by carbon
         dioxide fire extinguishers.
         [PJC.]

   Adiabatic line or curve, a curve exhibiting the
      variations of pressure and volume of a fluid when it
      expands without either receiving or giving out heat.
      --Rankine.
      [1913 Webster]

WordNet (r) 3.0 (2006):

adiabatic
    adj 1: occurring without loss or gain of heat; "adiabatic
           expansion" [ant: diabatic]