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 Global Financial Crisis had saddled GE Capital, long its biggest profitmaker, with mountainous debt. — Shawn Tully, Fortune, 23 July 2026

With a focus on sustainability and self-reliance similar to that of SECMOL, the institute is a higher-education center that awards fellowships for work on climate-friendly innovations that benefit communities in Ladakh and other mountainous regions. — Encyclopedia Britannica, 21 July 2026

One target site appeared to be in a valley of a mountainous region. — Jon Gambrell, Chicago Tribune, 19 July 2026

The uneven elevation of Spain’s mountainous regions could obstruct viewing the eclipse, as could a line of trees or a smattering of buildings. — Catherine Tansey, Condé Nast Traveler, 17 July 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