boulder
noun
a detached and rounded or worn rock, especially a large one.
Showing results for boulder.
Search instead for
Wouldbe.
boulder
1 American
[bohl-der]
/ ˈboʊl dər /
Or
bowlder
noun
-
boulders
plural
Boulder
2
American
[bohl-der]
/ ˈboʊl dər /
noun
boulder
British
/ ˈbəʊldə /
noun
-
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
-
geology a rock fragment with a diameter greater than 256 mm and thus bigger than a cobble
Other Word Forms
Derived Forms
Inflected Forms
Nouns
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
Explanation
A boulder is a rock — a big one. Scientists often think of a boulder in more technical terms than we do. They use the word to describe not just a big rock, but a rock that some natural force — a river, a glacier or the like — has moved from its original location to its present one. A good way to remember all this is to think of Boulder, a city in Colorado that stands in the middle of the Rocky Mountains, and is, no doubt, full of boulders.
Vocabulary lists containing boulder
"Mending Wall," by Robert Frost
Looking to grow your vocabulary? Check out this interactive, curated word list from our team of English language specialists at Vocabulary.com – one of over 17,000 lists we've built to help learners worldwide!
Earth Science - Middle School
Interested in learning more words like this one? Our team at Vocabulary.com has got you covered! You can review flashcards, quiz yourself, practice spelling, and more – and it's all completely free to use!
Earth Science - High School
Want to remember this word for good? Start your learning journey today with our library of interactive, themed word lists built by the experts at Vocabulary.com – we'll help you make the most of your study time!
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.
See Examples For:
Company dancer Lloyd Knight, costumed as the Preacher in “Spring” and captured in a determined stance on a boulder, faces the book’s last page, which quotes Graham: “Dancers are the messengers of the gods.”
From The Wall Street Journal ● Jun. 9, 2026
Larger incoming objects, such as boulder sized rocks that create especially bright flashes, are known as bolides or fireballs.
From Science Daily ● May 14, 2026
Olympic rock climbing champion Toby Roberts - who won gold in the boulder and lead event at Paris 2024 - was also made an MBE on Tuesday.
From BBC ● May 5, 2026
"It's not a piece of dust, but it's not a meter-size boulder, either."
From Barron's ● Apr. 8, 2026
She scrambled higher until she was at the top of a huge boulder that leaned out over the clearing.
From "A Girl Named Disaster" by Nancy Farmer
Co-author Dr David Wilson, research associate at the University of Colorado Boulder, explained their findings revealed some unusual activity.
From BBC ● Jul. 14, 2026
More broadly, recent research External link from the University of Colorado Boulder finds that after an ICE surge, employment among remaining immigrants declines 4% on average.
From Barron's ● Jun. 25, 2026
But Boulder could determine whether accountability arrives first.
From Slate ● Jun. 25, 2026
"It's incredible to think there was once a world this large," said Aaron Bell, an assistant research professor in the Department of Earth Science at the University of Colorado Boulder.
From Science Daily ● Jun. 23, 2026
For nine-year-old Joe, Boulder City offered an astounding cornucopia of delights.
From "The Boys in the Boat: Nine Americans and Their Epic Quest for Gold at the 1936 Berlin Olympics" by Daniel James Brown
Shannon, 11, was on a school residential trip on Dartmoor in Devon when her leg got trapped between enormous granite boulders on Hound Tor on Tuesday.
From BBC ● Jun. 27, 2026
Photos and a video Aiello provided show bladed wire snaking around the decomposing animal’s neck and curved horns, as well as the front legs, in a desert landscape dotted with boulders.
From Los Angeles Times ● Jun. 3, 2026
Stream engineering aims to improve habitats and water flow, for example by building dams or placing boulders in a stream, and these efforts have cost hundreds of millions of dollars over the years.
From Slate ● Apr. 28, 2026
A giant atrium was planned inside the structure where hologram images of spaceships and floating boulders whiz by visitors.
From The Wall Street Journal ● Apr. 6, 2026
By this time, several archaeologists had joined the expedition and immediately ordered that the powerful naval vessel Mykali be brought back from Athens to aid in the removal of the boulders.
From "Shipwrecked!" by Martin W. Sandler
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.
