Wikipedia
Mesotherm
A mesotherm (from Greek μέσος mesos "intermediate" and thermē "heat") is a type of animal with a thermoregulatory strategy intermediate to cold-blooded ectotherms and warm-blooded endotherms.
Usage examples of "mesotherm".
No one had ever measured how deep it was in the middle, but Professor Challenger had found it was full of fish and carried a fine population of fish-eating monsters—crocodiles, mesotherm reptiles, and aquatic therapsids.