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

Until recently, Rock Springs' main monument was a small plaque fixed to a boulder to recognize the 28 killed in the massacre. —Jenna McMurtry, NPR, 28 Sep. 2025

The seafloor is mainly mud and sand because stones and boulders were removed for construction in the 1800s and 1900s. —Sujita Sinha, Interesting Engineering, 26 Sep. 2025

The Arne bent-toed gecko was found in the evening on rocky boulders and near the mouth of a small cave that sat along a stream, according to the study. —Irene Wright, Miami Herald, 25 Sep. 2025

Approximately 100 trees and 100 tons of boulder were brought in, creating privacy at this property that blends luxury with architectural inspiration drawn from one of Michigan’s most celebrated designers. —Brendel Clark, Freep.com, 25 Sep. 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