plural dams
: a structure that is built across a river or stream to stop water from flowing
The government has plans to build a dam and flood the valley.
There's a beaver dam [=a dam built by beavers] in the stream behind my house.
dams; dammed; damming
: to build a dam across (a river or stream)
Beavers dammed the stream.
—often + upThey dammed up the river.
plural dams
technical
: the female parent of some animals (such as horses)
the foal's dam
Cite this Entry
“Dam.” Merriam-Webster.com Simple Definition, Merriam-Webster, https://www.merriam-webster.com/simple/dam. Accessed 18 Apr. 2026.
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