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

Overlooking the mountainous border between Austria and Italy, Weißseespitze is an alpine glacier. —Nidhi Sharma, Popular Science, 13 Mar. 2026

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, 13 Mar. 2026

Not only are the beaches less crowded (but no less beautiful), the surrounding area is also strikingly green and mountainous—especially on the drive in from the airport. —Annie Daly, Vogue, 10 Mar. 2026

Two live conflicts in this same broken, mountainous arc mean risks have more than doubled. —Mihir Sharma, Twin Cities, 8 Mar. 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