xe·ro·ther·mic \| ̷ ̷ ̷ ̷|thərmik\adjective Etymology:xer- + thermic 1. a.: being hot and dry : characterized by heat and dryness < a xerothermic climate > < a prolonged postglacial xerothermic period > b.: concerned with or stressing the significance of xerothermic climate < a xerothermic theory > 2.: adapted to or thriving in a xerothermic environment < xerothermic insects >