flood plain

American  

Or floodplain

noun

1. a nearly flat plain along the course of a stream or river that is naturally subject to flooding.

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flood plain British  

noun

1. the flat area bordering a river, composed of sediment deposited during flooding

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Etymology

Origin of flood plain

First recorded in 1870–75

Example Sentences

That designation involves even more restrictions than the 100-year flood plain, generally prohibiting new construction and significant renovations to existing buildings.

From The Wall Street Journal • Oct. 19, 2025

He even ordered the Army Corps of Engineers to release millions of gallons into a flood plain and then weirdly claimed that he'd "invaded" Los Angeles and solved its water problem.

From Salon • Jun. 9, 2025

And an additional 777 miles of roadway would be in the new flood plain, nearly tripling the at-risk total to 1,212 miles of road.

From Los Angeles Times • Apr. 30, 2025

Water voles now roam the network of channels, streams, and ponds the beavers use to navigate the flood plain.

From BBC • Feb. 28, 2025

Near the far edge of the flood plain I find Alice’s footsteps in a stretch of muddy sand.

From "On the Far Side of the Mountain" by Jean Craighead George