THERMAL

I. adjective Etymology: Greek thermē Date: 1756 of, relating to, or marked by the presence of hot springs , 2. of, relating to, or caused by heat , being or involving a state of matter dependent upon temperature , having low energies of the order of those due to ~ agitation , designed (as with insulating air spaces) to prevent the dissipation of body heat , ~ly adverb II. noun Date: 1933 a rising body of warm air