-therm \ˌ ̷ ̷\noun combining form (-s) Etymology: Greek thermē heat, from thermos hot 1.[probably from French -therme, from Greek thermē heat] a.: plant accustomed to a (specified) type of heat < megatherm > < microtherm > < xerotherm > b.: animal having a (specified) body temperature < ectotherm > < endotherm > 2.: thermic line < isobathytherm >