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
WordReference Random House Learner's Dictionary of American English © 2026
WordReference Random House Unabridged Dictionary of American English © 2026
boul•der
(bōl′dər),USA pronunciation n.
boul′dered, adj.
boul′der•y, adj.
Boul•der (bōl′dər),USA pronunciation n.
- Geologya detached and rounded or worn rock, esp. a large one.
- Old Swedish bulder) + sten stone
- Scandinavian; compare dialect, dialectal Swedish bullersten big stone (in a stream), equivalent. to buller rumbling noise (
- 1610–20; short for boulder stone; Middle English bulderston
boul′der•y, adj.
Boul•der (bōl′dər),USA pronunciation n.
- Place Namesa city in N Colorado. 76,685.
Collins Concise English Dictionary © HarperCollins Publishers::
'Boulder' also found in these entries (note: many are not synonyms or translations):
Black Canyon
- Boulder Canyon
- Boulder Dam
- Hoover Dam
- Kalgoorlie
- Oneida
- Rocky Mountain flowering raspberry
- boulder clay
- boulder raspberry
- bouldering
- bowlder
- coal ball
- cobble
- cobblestone
- colorado
- dreikanter
- einkanter
- erratic
- gibber
- grit
- rock
- rocking stone
- sarsen
- silex
- stone
- till