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

This area is perfect for those looking to escape the tropical heat of the coast and immerse themselves in a cooler, mountainous environment. —Condé Nast Traveler, 11 June 2026

Prior to European expansion and colonization in the West, two different wolf ecotypes — one at home on the plains and one more suited to mountainous terrain — may have met in Wyoming. —Natalie Krebs, Outdoor Life, 11 June 2026

The Blue Ridge Parkway is nearly 500 miles of a scenic, mountainous road that stretches from Virginia to North Carolina. —Usa Today Network, USA Today, 10 June 2026

East of the Ohio River, elk lived throughout the Appalachian Mountains from South Carolina to New York and were reported to have been most abundant in the mountainous areas of the Cumberland and Allegheny Plateaus. —Literary Hub, 10 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