Word Study
isocheim
CIDE DICTIONARY
isocheim, n. [Iso- + Gr. , , winter.].
A line connecting places on the earth having the same mean winter temperature. Cf. Isothere.
OXFORD DICTIONARY
isocheim, n. a line on a map connecting places having the same average temperature in winter.
Etymology
ISO- + Gk kheima winter weather
For further exploring for "isocheim" in Webster Dictionary Online