ec·to·ther·mic 
(ĕk′tə-thûrmĭk) also ec·to·ther·mal (ĕk′tə-thûrməl)
(ĕk′tə-thûrmĭk) also ec·to·ther·mal (ĕk′tə-thûrməl)adj.
Of or relating to an organism that regulates its body temperature largely by exchanging heat with its surroundings; cold-blooded.