thermal

(noun) rising current of warm air.

(adj) relating to or associated with heat. Synonyms: thermal (vs. nonthermal), thermic, caloric. Examples: "Thermal movements of molecules." "Thermal capacity." "Thermic energy." "The caloric effect of sunlight."

(adj) of or relating to a hot spring. Example: "Thermal water."

(adj) caused by or designed to retain heat. Examples: "A thermal burn." "Thermal underwear."