Synonyms for Mountainous (same or very similar meaning)
WordNet sense 1 (having hills and crags):
craggy, hilly, cragged
WordNet sense 2 (having or caused by an irregular surface):
rough, unsmooth
WordNet sense 3 (above average in size or number or quantity or magnitude or extent):
big, large
WordNet sense 4 (used of high or hilly country):
highland, upland
From the ODE community, based on WordNet
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