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

Don’t miss the adventures of the African penguin colony that lives on a white-sand beach named for its truck-sized boulders. —Katie Jackson, Travel + Leisure, 1 Dec. 2025

The film, directed by Danny Boyle, is a biographical drama about Aron Ralston, who became trapped by a boulder in a Utah canyon. —Marta Balaga, Variety, 28 Nov. 2025

Because water has been found in lunar rock before, embedded in crystals of volcanic glass or mineral grains, lasering promising boulders may prove important. —Elizabeth Howell, Space.com, 24 Nov. 2025

And just outside the gates of Purgatory, near the base of the mountain, Dante comes upon an old friend called Belacqua, lounging in the shade of a boulder. —Claudia Roth Pierpont, New Yorker, 24 Nov. 2025

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