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

Back then, the tall angled ceilings seemed to soar and the breakfast combos looked mountainous. —Stephanie Breijo, Los Angeles Times, 12 May 2026

Jamaica is a beautiful island with white beaches; a green, mountainous interior; and, despite its small size, one of the most recognizable cultures in the world. —Anne Applebaum, The Atlantic, 12 May 2026

Paro International Airport in Bhutan is one of the world’s most technically demanding, with only about 50 certified pilots navigating its mountainous approach. —Chris Dong, Travel + Leisure, 12 May 2026

Sargassum is washing up on South Florida beaches in mountainous amounts, rotting into a gag-worthy mush. —Ashley Miznazi, Miami Herald, 11 May 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