adiabatic line

from 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]