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.
- upper-class
- upperclassman
- upper crust
- upper-crust
- uppercut
- Upper Egypt
- upper GI series
- upper hand
- Upper Klamath Lake
- uppermost
- Upper Palatinate
- Upper Peninsula
- Upper Silesia
- Upper Sorbian
- Upper Tunguska
- Upper Volta
- Upper Volta
- Upper Voltan
- uppish
- uppishly
- uppitiness
- uppity
- uppityness
- Uppsala
- up quark