boulder

noun

boul·​der ˈbōl-dər 

variants or less commonly bowlder

: a detached and rounded or much-worn mass of rock

bouldered

ˈbōl-dərd 

adjective

bouldery

ˈbōl-d(ə-)rē 

adjective

Examples of boulder in a Sentence

Recent Examples on the Web

It's filled with crystal-clear waters that flow over limestone boulders before eventually merging into the river. —Talia Avakian, Travel + Leisure, 14 May 2026

Boulders South Course Scottsdale, Arizona Swing past massive granite boulders and cacti at The Boulders South Course in Scottsdale, Arizona. —Megan Dubois, USA Today, 13 May 2026

Lunar regolith, a loose agglomeration of volcanic ash, grit, stones and boulders, covers the moon to depths of perhaps 65 feet, topped by a thin layer of gritty, sharp volcanic dust. —Dan Vergano, Scientific American, 11 May 2026

Kent’s created what look like tide pools with succulents and shells, surrounded by lava and boulders. —Caron Golden, San Diego Union-Tribune, 9 May 2026

Word History

Etymology

short for boulder stone, from Middle English bulder ston, partial translation of a word of Scandinavian origin; akin to Swedish dialect bullersten large stone in a stream, from buller noise + sten stone

First Known Use

1607, in the meaning defined above

Rhymes for boulder

• bolder
• bowlder
• colder
• folder
• golder
• holder
• molder
• moulder
• older
• polder
• shoulder
• beholder

Kids Definition

boulder

noun

boul·​der ˈbōl-dər 

: a large detached and rounded or worn mass of rock

Geographical Definition

Boulder

geographical name

Boul·​der ˈbōl-dər 

city northwest of Denver in north central Colorado population 97,385