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

This secluded and mountainous chunk of property offers more elevation change than most of the American Midwest combined—and thanks to the recent 40-plus inches of rain, a similarly Midwestern potential to produce ungodly amounts of mud. —Byron Hurd, The Drive, 22 Jan. 2026

Since the 1990s, Armenia and Azerbaijan have fought over the mountainous region of Nagorno-Karabakh, which is internationally recognized as part of Azerbaijan, and more than 40,000 people have been killed throughout the conflict. —Mark Temnycky, Forbes.com, 22 Jan. 2026

The same fate befalls the HAKOS Astro Guest Farm, a remote mountainous escape for amateur astronomers. —Jamie Carter, Space.com, 20 Jan. 2026

The body of the victim was recovered from the remote mountainous area, the report continues. —David Chiu, PEOPLE, 20 Jan. 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