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

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, 8 Jan. 2026

They have been widely cultivated for centuries, but their wild ancestors are native to the mountainous regions of Central Asia. —Laura Baisas, Popular Science, 7 Jan. 2026

Big Bend officials plan to replace the lodge and the water line system for that area, a mountainous part of the park home to some of its most popular hiking trails, the Lost Mine and Window trails. —Liz Teitz, San Antonio Express-News, 5 Jan. 2026

The event would put Denver in the national spotlight, giving people from across the country a look at the city’s mountainous skyline and revamped downtown. —Elliott Wenzler, Denver Post, 4 Jan. 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