Synonyms of mountainous

1 Syllable

tall, huge, big, giant

2 Syllables

highland, huger, massiest, massy, rugged, hillier, whaling, whopping, hugest, hilly, mammoth, massier

3 Syllables

snowcapped, alpine, furrowed, montane, humungous, cyclopean, pythonic, towering, gargantuan, enormous, gigantic, walloping, colossal, leviathan, massive

4 Syllables

monumental, super-duper, bunyanesque, gigantesque, mastodonic, weatherbeaten, behemothic

5 Syllables

elephantine, super-colossal