mountainous

adjective

moun·​tain·​ous ˈmau̇n-tə-nəs 

ˈmau̇nt-nəs

1

: containing many mountains

2

: resembling a mountain : huge

mountainously adverb

mountainousness noun

Synonyms

• vast
• huge
• gigantic
• enormous
• giant
• massive
• tremendous
• colossal
• mammoth
• immense
• astronomical
• monumental
• astronomic
• monstrous

Examples of mountainous in a Sentence

the seemingly mountainous obstacles he had to overcome while growing up

Recent Examples on the Web

Some towers in remote deserts or mountainous regions send data through satellites, and anyone within the satellite’s coverage area can potentially intercept those signals. —Kaif Shaikh, Interesting Engineering, 14 Oct. 2025

These early-season conditions threaten to make travel hazardous, especially in the mountainous corridors popular with commuters and tourists. —Anna Skinner, MSNBC Newsweek, 14 Oct. 2025

The material was sensitive, labyrinthine, and mountainous in scope. —Literary Hub, 14 Oct. 2025

The militaries of both nations have frequently clashed along their shared border, a nearly 1,600-mile-long line that snakes along mountainous areas. —Zia Ur-Rehman, New York Times, 12 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