mountainous

adjective

moun·​tain·​ous ˈmau̇n-tə-nəs 

ˈmau̇nt-nəs

1

: containing many mountains

2

: resembling a mountain : huge

mountainously adverb

mountainousness noun

Synonyms

• vast
• huge
• gigantic
• enormous
• giant
• massive
• tremendous
• colossal
• mammoth
• immense
• astronomical
• monumental
• astronomic
• monstrous

Examples of mountainous in a Sentence

the seemingly mountainous obstacles he had to overcome while growing up

Recent Examples on the Web

Ragasa brought finance hub Hong Kong and swathes of southern China to a standstill on Wednesday, after barreling through remote islands in the Philippines and mountainous regions of Taiwan. —Jessie Yeung, CNN Money, 24 Sep. 2025

Back then, my relatively limited knowledge of food came from binge-watching Ina Garten and collecting a mountainous pile of cookbooks that threatened to take over my bedroom. —Alexandra Emanuelli, Travel + Leisure, 21 Sep. 2025

During the months-long manhunt, federal and state agencies searched hundreds of square miles, looking through remote and mountainous terrain. —Thao Nguyen, USA Today, 19 Sep. 2025

The tough, ingenious (and dirt-poor) Houthis, protected by Yemen’s mountainous interior, fought back with the tenacity of drug-resistant microbes. —Seth Harp, Harpers Magazine, 19 Sep. 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