flood plain

American

Or floodplain

noun

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

flood plain British

noun

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

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of flood plain

First recorded in 1870–75

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

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

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

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023