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

Sliding glass doors opened onto a spacious deck overlooking boulders, ornamental grasses and mature trees. — Heather Senison, New York Times, 5 Nov. 2026

While most bits of ice and rock that burn up are the size of dust grains or pebbles, fireballs arise from debris ranging from the size of a marble to that of a small boulder. — Dharma Niles, CNN Money, 4 Nov. 2026

The heavy rain washed out part of a main highway between Flagstaff and Sedona, mangling guard rails and littering the road with boulders and trees. — Christopher Weber, Los Angeles Times, 2 Nov. 2026

The city launched the naming contest after the 50-to boulder was found during construction. — Natalie McMillan, CBS News, 2 Nov. 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