Isogeothermal \I`so*ge`o*ther"mal\, Isogeothermic \I`so*ge`o*ther"mic\, a. Pertaining to, having the nature of, or marking, isogeotherms; as, an isogeothermal line or surface; as isogeothermal chart. -- n. An isogeotherm. [1913 Webster]