mountainous

adjective

moun·​tain·​ous ˈmau̇n-tə-nəs 

ˈmau̇nt-nəs

1

: containing many mountains

mountainous wilderness

2

: resembling a mountain : huge

a stormy ocean with mountainous waves

mountainously adverb

mountainousness noun

Synonyms of mountainous

• vast
• huge
• gigantic
• enormous
• giant
• massive
• tremendous
• colossal
• mammoth
• immense
• astronomical
• monumental
• monstrous

Examples of mountainous in a Sentence

the seemingly mountainous obstacles he had to overcome while growing up

Recent Examples on the Web

These many watering holes are reflective of the Lone Star state's varied geographic regions, from bald cypress swamps to mountainous desert lakes. —Kaitlyn Yarborough, Southern Living, 16 June 2026

Rescue teams with search dogs had been dispatched to the mountainous area in Haixi prefecture on the Tibetan plateau. —ABC News, 16 June 2026

Sleeping on an air mattress was as foreign to her as setting her eyes on a mountainous horizon. —Brad Ryan, PEOPLE, 13 June 2026

This area is perfect for those looking to escape the tropical heat of the coast and immerse themselves in a cooler, mountainous environment. —Condé Nast Traveler, 11 June 2026

Word History

Etymology

Middle English mounteynous, borrowed from Anglo-French muntaignus, from muntaigne, mountaigne mountain + -us -ous

First Known Use

14th century, in the meaning defined at sense 1

Kids Definition

mountainous

adjective

moun·​tain·​ous ˈmau̇nt-ᵊn-əs 

-nəs

1

: having many mountains

2

: resembling a mountain : huge