Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
cismontane is an adjective meaning "on this (the speaker's) side of the mountains". It carries one recorded sense.
on this (the speaker's) side of the mountains
“a contest in Virginia between a cismontane and a tramontane people”
Definitions, synonyms and semantic relations for cismontane come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.