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 hurricane posed the biggest threat to the rural and mountainous coast of Michoacan and Guerrero, which is scattered with small tourist towns and ports. — Megan Janetsky, Arkansas Online, 25 Sep. 2026

Medical supplies and fuel are running short after key supply routes between Mokha and Taiz were largely cut off, forcing convoys onto mountainous roads unsuitable for large trucks. — Fatma Khaled, Los Angeles Times, 25 Sep. 2026

The region most under threat from Polo is rural and mountainous, scattered with a few small tourist towns and ports. — Megan Janetsky, Chicago Tribune, 24 Sep. 2026

From there, head south toward the Mani peninsula’s stone tower houses or inland to mountainous Arcadia. — Paul Jebara, Condé Nast Traveler, 17 Sep. 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