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

The asteroid's rapid rotation period of less than one hour aligns with what scientists would expect from either a large boulder ejected from the Moon's surface or a fragment broken off from a larger lunar object. —Tom Rogers, Newsweek, 25 Nov. 2024

But using higher-frequency blue light is like switching to boulders. —Charlie Wood, Quanta Magazine, 30 Oct. 2024

The edgy route twists through the forest dodging boulders and skimming ravines before encountering a gorgeous passage lined with aspen trees. —Mare Czinar, The Arizona Republic, 26 Sep. 2024

An array of park trails are within a 25-minute drive of your tower, including Sunday Gulch Trailhead, which weaves by dramatic van-sized boulders for three miles, or the take the route up Black Elk Peak, South Dakota’s highest point. —Stephanie Vermillion, Outside Online, 6 Nov. 2024

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

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