Dictionary.com
Thesaurus.com
Synonyms

mountainous

American  
[moun-tn-uhs] / ˈmaʊn tn əs /

adjective

  1. abounding in mountains.

    a mountainous wilderness.

  2. of the nature of a mountain.

  3. resembling a mountain or mountains, as being very large and high.

    mountainous waves.


mountainous British  
/ ˈmaʊntɪnəs /

adjective

  1. of or relating to mountains

    a mountainous region

  2. like a mountain, esp in size or impressiveness

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Other Word Forms

  • mountainously adverb
  • mountainousness noun
  • nonmountainous adjective
  • nonmountainously adverb
  • semimountainous adjective
  • semimountainously adverb
  • unmountainous adjective

Etymology

Origin of mountainous

First recorded in 1400–50, mountainous is from the late Middle English word mounteynous. See mountain, -ous

Vocabulary lists containing mountainous

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

It is a mountainous road with sharp turns, and an image shared by the emergency services appears to show it crashing near a hairpin bend.

From BBC • Apr. 10, 2026

But as he went deeper into hiding in the mountainous terrain, communication went in and out as U.S. officials sought to keep track of his location.

From The Wall Street Journal • Apr. 5, 2026

The mountainous terrain is rugged and covered by thick bush.

From BBC • Apr. 3, 2026

The area's mountainous geography makes it doubly vulnerable.

From Barron's • Apr. 3, 2026

Michelangelo had placed his enormous hands on his mountainous belly.

From "The Inquisitor's Tale" by Adam Gidwitz