boulder

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.

Definitions of boulder
1

n a large smooth mass of rock detached from its place of origin

Synonyms:
bowlder
Examples:
Plymouth Rock
a boulder in Plymouth supposed to be where the Pilgrims disembarked from the Mayflower
Types:
glacial boulder
a boulder that has been carried by a glacier to a place far distant from its place of origin
river boulder
a boulder that has been carried by a river to a place remote from its place of origin
shore boulder
a boulder found on a shore remote from its place of origin
Type of:
rock, stone
a lump or mass of hard consolidated mineral matter

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