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

Hailing from mountainous southwestern Virginia, the Stanley Brothers – Ralph and Carter – were a foundational act in bluegrass whose music has influenced generations of artists in a variety of genres. —Chris Willman, Variety, 20 Mar. 2026

Soon, there could be military boots on the ground crossing into the Islamic Republic of Iran from this terrain of fertile valleys, deep gorges and ancient Mesopotamian trade routes perched below the mountainous border dividing Iraq and Iran. —Younes Mohammad, USA Today, 15 Mar. 2026

The island’s interior is mountainous and primitive, covered with mule tracks and drought-resistant vegetation. —Kristina Kasparian, Travel + Leisure, 15 Mar. 2026

Servicing a mountainous areas like Escondido drives up costs, as an expensive network of pipes and pump stations is needed to move water up and down considerable inclines, said Kyle Morgan, the city’s acting director of utilities and wastewater. —Lucas Robinson, San Diego Union-Tribune, 15 Mar. 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