The Collaborative International Dictionary
Intermontane \In`ter*mon"tane\, a. [Pref. inter- + L. montanus belonging to a mountain, fr. mons, montis, mountain.] Between mountains; as, intermontane soil.
a. Between mountains.
Intermontane is a physiographic adjective formed from the prefix "inter-" ("signifying among, between, amid, during, within, mutual, reciprocal) and the adjective "montane" ("inhabiting, or growing in mountainous regions, especially cool, moist upland slopes below the timberline.")
The corresponding physiographic noun is intermountain, while the noun intermontane is an ecologic noun meaning among, between, amid, or within "flora and fauna of a montane habitat." As an example, an alpine region would be an intermontane for a species that migrates between a glacial region and a subalpine region.