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

Set in the small town of Kharkams, in South Africa’s mountainous Kamiesberg region, the film follows an elderly goat herder, Hettie, who falls victim to a scam promising long-overdue reparations for her father’s WWII service. —Christopher Vourlias, Variety, 6 Mar. 2026

Estimates of the population range between 25 million and 45 million worldwide, with most living in the mountainous region that stretches across parts of western Iran, eastern Turkey, northern Iraq and Syria, and Armenia. —Lauren Kent, CNN Money, 5 Mar. 2026

Head to Kootenay, a mountainous region in southeast British Columbia—specifically to the town of Creston. —Jeffrey Kluger, Time, 5 Mar. 2026

Mountain West Hummingbirds like the broad-tailed, black-chinned, rufous, and calliope varieties arrive in the mountainous West in spring once flowers begin to bloom. —Sydney Wingfield, Martha Stewart, 4 Mar. 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