isotherombrose

from The Collaborative International Dictionary of English v.0.48

Isotherombrose \I*soth`er*om"brose\, n. [Iso- + Gr. qe`ros
   summer + 'o`mbros rain.] (Phys. Geog)
   A line connecting or marking points on the earth's surface,
   which have the same mean summer rainfall.
   [1913 Webster]