• synonyms


or bowl·der

See more synonyms for boulder on Thesaurus.com
  1. a detached and rounded or worn rock, especially a large one.
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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
Related formsboul·dered, adjectiveboul·der·y, adjective
Can be confusedbolder boulderboulder cobblestone granule pebble rock stone


  1. a city in N Colorado.
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Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Related Words for boulder

metal, rubble, lava, earth, gravel, slab, plate, stone, slice, ingot, wedge, rod, lump, hunk, strip, piece, crystal, grain, rock, gem

Examples from the Web for boulder

Contemporary Examples of boulder

Historical Examples of boulder

  • We dropped behind a boulder and Tse-tse counted while I lifted every scent.

    The Trail Book

    Mary Austin

  • Linda rushed to the boulder and knelt again, but she could get no response to her questions.

    Her Father's Daughter

    Gene Stratton-Porter

  • He stooped; seized a boulder, hurled it at the oncoming Lee.

    The World Beyond

    Raymond King Cummings

  • He was behind a boulder, not too dissimilar to Calhoun's breastwork.

    Pariah Planet

    Murray Leinster

  • The girl stumbled, struck her head against a boulder, and lay still.

    Loot of the Void

    Edwin K. Sloat

British Dictionary definitions for boulder


  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
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Derived Formsbouldery, adjective

Word Origin for boulder

C13: probably of Scandinavian origin; compare Swedish dialect bullersten, from Old Swedish bulder rumbling + sten stone
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

Word Origin and History for boulder


1670s, variant of Middle English bulder (c.1300), from a Scandinavian source akin to Swedish dialectal bullersten "noisy stone" (large stone in a stream, causing water to roar around it), from bullra "to roar" + sten "stone." Or the first element might be from *buller- "round object," from Proto-Germanic *bul-, from PIE *bhel- (2) "to inflate, swell" (see bole).

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Online Etymology Dictionary, © 2010 Douglas Harper