ophidian vs poikilothermic

ophidian

adj
  • Of or pertaining to the suborder Serpentes; of, related to, or characteristic of a snake or serpent. 

noun
  • Any species of the suborder Serpentes; a snake or serpent. 

poikilothermic

adj
  • Having a body temperature that varies depending on the outside temperature. 

How often have the words ophidian and poikilothermic occurred in a corpus of books? (source: Google Ngram Viewer )