Pronunciation: (thûr'mul),[key] —adj. 1. Also,thermic.of, pertaining to, or caused by heat or temperature: thermal capacity. 2. of, pertaining to, or of the nature of thermae: thermal waters. 3. designed to aid in or promote the retention of body heat: a thermal blanket.
—n. 1. Meteorol.a rising air current caused by heating from the underlying surface, esp. such a current when not producing a cloud.
2. thermals.See thermal underwear.