Synonyms of mountainous in English:

mountainous


See US English definition of mountainous

See UK English definition of mountainous

See Spanish definition of montañoso

adjective

1‘a mountainous region’

SYNONYMS
hilly, craggy, rocky, alpine, high, steep, precipitous
upland, highland
ANTONYMS

flat

2‘mountainous waves’

SYNONYMS
huge, enormous, gigantic, massive, very big, very large, great, giant, colossal, mammoth, vast, immense, tremendous, mighty, formidable, staggering, monumental, Herculean, epic, prodigious, monstrous, titanic, towering, king-sized, king-size, gargantuan, substantial
informal mega, monster, whopping, whopping great, thumping, thumping great, humongous, jumbo, hulking, astronomical, astronomic
British informal whacking, whacking great, ginormous
ANTONYMS

tiny, minute