The Collaborative International Dictionary of English v.0.48:

Poikilothermal \Poi`ki*lo*ther"mal\ (-th[~e]r"mal),
Poikilothermic \Poi`ki*lo*ther"mic\ (-th[~e]r"m[i^]k), a. [Gr.
   poiki`los changeable + E. thermal, thermic.] (Physiol.)
   Having a varying body temperature. See Homoiothermal.
   [1913 Webster]