mountainous

adjective

moun·​tain·​ous ˈmau̇n-tə-nəs 

ˈmau̇nt-nəs

1

: containing many mountains

2

: resembling a mountain : huge

mountainously adverb

mountainousness noun

Synonyms

• astronomical
• astronomic
• Brobdingnagian
• bumper
• colossal
• cosmic
• cosmical
• cyclopean
• elephantine
• enormous
• galactic
• gargantuan
• giant
• gigantesque
• gigantic
• grand
• herculean
• heroic
• heroical
• Himalayan
• huge
• humongous
• humungous
• immense
• jumbo
• king-size
• king-sized
• leviathan
• mammoth
• massive
• mega
• mighty
• monster
• monstrous
• monumental
• oceanic
• pharaonic
• planetary
• prodigious
• super
• super-duper
• supersize
• supersized
• titanic
• tremendous
• vast
• vasty
• walloping
• whacking
• whopping

Examples of mountainous in a Sentence

the seemingly mountainous obstacles he had to overcome while growing up

Recent Examples on the Web

This mountainous region, part of the Sierra Madre Oriental, rises sharply from the valley floor, creating a landscape of deep ravines, dense forests, and extreme ecological diversity. —Lauren Mowery, Forbes, 28 Feb. 2025

Much of the winter snow in 2023 and 2024 came from atmospheric rivers that brought heavy precipitation to mountainous regions. —Dan Perry, Newsweek, 28 Feb. 2025

The violence unfolded on Feb. 3 at a home in Show Low, a small mountainous community about 180 miles outside of Phoenix. —Jessica Schladebeck, New York Daily News, 25 Feb. 2025

Consider the airplanes and helicopters that the California Department of Forestry and Fire Protection keeps ready to fight fires in mountainous, difficult-to-reach areas. —Jeff Goodell, Rolling Stone, 13 Feb. 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