Source : Webster's Revised Unabridged Dictionary (1913)

Endothermic \En`do*ther"mic\, a. [Pref. endo- + thermic.]
   (Chem.)
   Designating, or pert. to, a reaction which occurs with
   absorption of heat; formed by such a reaction; as, an
   endothermic substance; -- opposed to {exothermic}.

Source : WordNet®

endothermic
     adj : (of a chemical reaction or compound) occurring or formed
           with absorption of heat [syn: {endothermal}, {heat-absorbing}]
           [ant: {exothermic}]