a barrier to obstruct the flow of water, especially one of earth, masonry, etc., built across a stream or river.
a body of water confined by a dam.
any barrier resembling a dam.
a barrier of concrete, earth, etc, built across a river to create a body of water for a hydroelectric power station, domestic water supply, etc
a reservoir of water created by such a barrier
something that resembles or functions as a dam
1275–1325; Middle English < Middle Dutch, Middle Low German, dam; akin to Old English for-demman to stop up, block
1250–1300; Middle English; variant of dame
A barrier built to block the flow of water is called a dam. If you walk along a stream, you can see where beavers have built a dam out of mud and logs. As a verb, dam means to obstruct or blockade as with a dam. If the kids you're babysitting dam up the bathtub drain when you're not paying attention, the water might overflow and cause a waterfall into the living room downstairs. But water isn't the only thing that can be dammed. You shouldn't dam up your emotions — go ahead and scream if you need to.
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Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
A wide river of cropped hair, crisp T-shirts, and adrenaline stretching almost 500 feet to Herndon, where they’re held back by an invisible dam about to burst.
From Slate • Jun. 24, 2026
In October 2007, while scouring Google Earth, he discovered the largest beaver dam on the planet—a 2,700-foot-long structure in northern Alberta with a 17-acre lake backed up behind it.
From The Wall Street Journal • Jun. 19, 2026
Even during the original dedication of the dam and reservoir, conditions were dry enough for grass to grow across exposed lakebed.
From Science Daily • Jun. 18, 2026
Route 93, which goes across the top of the dam.
From Los Angeles Times • Jun. 1, 2026
The original village was submerged when a government dam was built in 1956.
From "Mountains Beyond Mountains" by Tracy Kidder and Michael French
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.
