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

The affordable passenger train travels between all five mountainous villages in Italy’s Cinque Terre region, running from spring until late fall. —Jessica Puckett, Condé Nast Traveler, 5 June 2026

They are found in every ecosystem, from desert to forest, from mountainous elevations to the plains. —Joshua Siskin, Oc Register, 4 June 2026

From the French-German border to the Mediterranean coast to the mountainous intersection of France, Italy, and Switzerland, these small towns and villages (all home to less than 15,000 people) offer a slower pace and warm French hospitality. —Evie Carrick, Travel + Leisure, 3 June 2026

Patagonia is presumably named after the mountainous region that spreads across Argentina and Chile in South America. —José Criales-Unzueta, Vanity Fair, 3 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