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

Charity group Good360 also donated generators that the Jamaican military is taking into mountainous regions still without power. —Amanda Rosa, Miami Herald, 3 Nov. 2025

The film is a deeply personal one for Neofotistos, who was born in Epirus, a mountainous region on Greece’s border with Albania, and grew up in a conservative family for whom religion and superstition were deeply intertwined. —Christopher Vourlias, Variety, 3 Nov. 2025

Backcountry Skiing the Traversée de Charlevoix The Traversée de Charlevoix covers 79 miles of mountainous wilderness in the heart of the Charlevoix biosphere region. —Outside, 3 Nov. 2025

The Milan Cortina Olympics will be spread out across northern Italy, covering an area of more than 10,000 square miles across seven regions ranging from dense, urban Milan to mountainous Livigno. —Andrew Greif, NBC news, 29 Oct. 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