The Collaborative International Dictionary of English v.0.48:

endoergic \endoergic\ adj.
   occurring with absorption of energy. [Narrower terms:
   endothermic] exoergic

   Syn: energy-absorbing.
        [WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

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.
   [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

endothermic
    adj 1: (of a chemical reaction or compound) occurring or formed
           with absorption of heat [syn: endothermic,
           endothermal, heat-absorbing] [ant: exothermal,
           exothermic, heat-releasing]