Wiktionary
isothermic
a. 1 (context physics English) (''Of a thermodynamic process'') during which the temperature remains constant. 2 (context meteorology English) Of equal or constant temperature with respect to space, volume, or pressure.
WordNet
isothermic
adj. of or relating to an isotherm
Usage examples of "isothermic".
Most terrestrial isothermic and posithermic creatures can survive to just above freezing temperatures as long as they don't stay that way too long.