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

According to Nahmias, the low-top shoe’s design is meant to capture the mountainous ranges that meet the water throughout California and features an upper inspired by a popular skate shoe paired with an exaggerated sole made of lightweight materials. — Stephen Garner, Footwear News, 24 June 2026

The history of Welsh food is deeply tied to the country’s rugged mountainous terrain—think hearty ingredients that could withstand the rainy weather like root vegetables and salted meats. — Carinne Geil Botta, Forbes.com, 23 June 2026

Winter brings peak ski season at Bachelor and the more mountainous crowds. — Sierra Vandervort, Travel + Leisure, 20 June 2026

These many watering holes are reflective of the Lone Star state's varied geographic regions, from bald cypress swamps to mountainous desert lakes. — Kaitlyn Yarborough, Southern Living, 16 June 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