I'so-gē'o-thērm, n.
n. [Gr. ἴσος, equal, γῆ, earth, and θέρμη, heat.] (Phys. Geog.) An imaginary line or curved surface passing beneath the earth's surface through points having the same mean temperature.
n. [Gr. ἴσος, equal, γῆ, earth, and θέρμη, heat.] (Phys. Geog.) An imaginary line or curved surface passing beneath the earth's surface through points having the same mean temperature.