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

Today, China’s rivers are dotted with hydropower projects, while cutting-edge transmission lines carry high-voltage electricity from rural and mountainous regions to the skyscrapers, AC units and electric vehicles of urban China. —Simone McCarthy, CNN Money, 17 Dec. 2025

The country is home to seven different regions, according to the Costa Rica Tourism Board, ranging from the coastal paradise of Guanacasteto to the mountainous Northern Plains. —Michael Cappetta, Travel + Leisure, 8 Dec. 2025

Fewer than 2,000 pandas survive in the wild, limited to mountainous regions in Sichuan, Shaanxi, and Gansu provinces. —Moná Thomas, PEOPLE, 8 Dec. 2025

For an easily reachable perch, try the Ridge View Trail on the eastern side or the Visitor Center Trail in the park’s mountainous western half. —Stephanie Vermillion, Outside, 8 Dec. 2025

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