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

Wedge bodysurfer Sean Starkey has been watching erosion change his beloved surf break in recent years and said the effects have never been so stark as in recent days, exposing rock boulders longtimers have never seen before. —Laylan Connelly, Oc Register, 18 June 2026

And the diversion structure no longer uses boulders to control the water flow. —Noelle Phillips, Denver Post, 18 June 2026

During the morning low tide, while there was still a small stretch of sand, excavators were working to pile large rip-rap boulders next to the base of the crumbling Pacifica Pier. —John Ramos, CBS News, 16 June 2026

The city declared a state of emergency and has since started repair work; last week, workers began moving 150 large boulders on either side of the pier’s abutment to stabilize it, said Pacifica City Manager Sean Charpentier. —Caelyn Pender, Mercury News, 15 June 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