boulder
noun
a detached and rounded or worn rock, especially a large one.
Showing results for boulder.
Search instead for
owlder.
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
Having squandered the good-will created by Sam Ryder's success, the BBC delegation now has the tricky task of pushing the boulder back up the hill.
From BBC ● May 17, 2026
"It's not a piece of dust, but it's not a meter-size boulder, either."
From Barron's ● Apr. 8, 2026
City crews placed a boulder over the manhole cover, a spokesperson who was at the scene Wednesday said but, by the following morning, the boulder had been moved.
From Los Angeles Times ● Mar. 25, 2026
Sammy went behind the boulder and came out holding a big grocery bag, which he set down before the fireplace.
From "Homecoming" by Cynthia Voigt
The latest discovery came Sunday at Boulder Beach on the western part of the Lake Mead National Recreation Area in Nevada, according to national park officials.
From Los Angeles Times ● Aug. 19, 2026
Researchers led by chemists at the University of Wisconsin-Madison, working with teams at Colorado State University and the University of Colorado Boulder, have now demonstrated a different approach to reaction design.
From Science Daily ● Aug. 9, 2026
Ann Lipton, a law professor at the University of Colorado, Boulder, said Trump knows the value of his statements and that the more he rattles markets, the more valuable his new service becomes.
From Barron's ● Aug. 4, 2026
The 18-year-old has been accepted to University of Colorado Boulder but deferred for a year.
From BBC ● Jul. 4, 2026
He remembered the mushrooms on the rotten logs in Boulder City.
From "The Boys in the Boat: Nine Americans and Their Epic Quest for Gold at the 1936 Berlin Olympics" by Daniel James Brown
Gantry cranes were washed away, silt and boulders jammed the headworks, and floodwaters entered the power house, knocking the plant offline.
From The Wall Street Journal ● Sep. 9, 2026
"There's boulders bigger than houses - I've never seen that before in my life. It's just an extraordinary operation," the former head of the International Tunnelling Association said.
From BBC ● Aug. 31, 2026
Photographs shared by the disaster office showed workers wading through churned mud and navigating vast boulders left by the floods.
From Barron's ● Aug. 30, 2026
So she hiked out to just beyond the Valley of the Moon trail, where the wire winds through piles of boulders.
From Los Angeles Times ● Jun. 3, 2026
Their latest portage wasn’t going well at all: One of the canoes had smashed into the boulders.
From "Death on the River of Doubt" by Samantha Seiple
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.
