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

Look for them on cottonwood, willow, aspen, or alder trees across northern and mountainous regions, according to the University of British Columbia. — Katie Hill, Outdoor Life, 6 Aug. 2026

His grandmother, Rina Laveder, had moved from the mountainous Dolomites in the Veneto region to Venezuela as a child. — Julia Buckley, CNN Money, 4 Aug. 2026

After today’s time trial, the race moves on to the harder mountainous stages. — Jessica Hopkins, New York Times, 4 Aug. 2026

The mountainous areas in the country’s central region are the worst affected by the severe weather, according to the government’s Disaster Management Center. — ABC News, 4 Aug. 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