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

The land sits on low ground and would need fill for any redesign, to get it above the Potomac River flood plain.

From The Wall Street Journal • Dec. 13, 2025

It might be that in an era of what researchers are calling “mega rain” events, a flood plain should now be off-limits.

From Salon • Jul. 10, 2025

Currently, more than 8,000 people live in flood plain areas along estuaries in the Cascadia coastal region.

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

It was a miniature model of the Greasy Grass River, the hills to the east of the village site, and the flood plain where the village had stood.

From "In the Footsteps of Crazy Horse" by Joseph Marshall III