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Boulder

1 American  
[bohl-der] / ˈboʊl dər /

noun

  1. a city in N Colorado.

boulder 2 American  
[bohl-der] / ˈboʊl dər /
Or bowlder

noun

  1. a detached and rounded or worn rock, especially a large one.

boulder British  
/ ˈbəʊldə /

noun

  1. a smooth rounded mass of rock that has a diameter greater than 25cm and that has been shaped by erosion and transported by ice or water from its original position

  2. geology a rock fragment with a diameter greater than 256 mm and thus bigger than a cobble

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Other Word Forms

  • bouldered adjective
  • bouldery adjective

Etymology

Origin of boulder

1610–20; short for boulder stone; Middle English bulderston < Scandinavian; compare dialectal Swedish bullersten big stone (in a stream), equivalent to buller rumbling noise (< Old Swedish bulder ) + sten stone

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

Due to the water’s high mineral content, the fall’s boulders have developed a spongy texture that allows you to climb barefoot while water gushes over your feet.

From The Wall Street Journal

Now I have more than a bundle to carry—I have a boulder.

From Literature

The kaolinite pieces observed by Perseverance range in size from small pebbles to large boulders.

From Science Daily

A 14-year-old girl decorated a large boulder off Greenland’s coast with the letters: “U.S.A. OK.”

From The Wall Street Journal

The two meet regularly to take on a terrifying nearby boulder.

From The Wall Street Journal

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.