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

At least one government soldier was killed and another critically wounded in clashes with the Houthis in the mountainous province of Taiz, Yemeni military officials told The Associated Press. — ABC News, 13 Aug. 2026

One thing Roberts well remembers is the mountainous paperwork international shipping once required. — Michael Ashley, Forbes.com, 12 Aug. 2026

Much of the damage from Monday’s earthquake has been concentrated in a mountainous, lush and culturally important region which helps to power Colombia’s economy and draws hundreds of thousands of tourists annually. — Michael Rios, CNN Money, 10 Aug. 2026

There were also reports of serious damage in Manizales, a city in Colombia’s mountainous coffee-growing region. — Antonio María Delgado, Miami Herald, 10 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