In hydrologic terms, the portion of a river valley that has been inundated by the river during historic floods.

flat area alongside a stream or river that is subject to flooding. Read more in the NG Education Encyclopedia

Typically, a low area adjacent to a river or other body of water that is subject to flooding.

Generally low-lying areas adjacent to a watercourse, tidal lengths of a river or the sea, where water flows in times of flood or would flow but for the presence of flood defences.

An area of land covered with water during river flooding. Flood plains are the basis of alluvial plains.

a strip of relatively flat and normally dry land alongside a stream, river, or lake that is covered by water during a flood.

The land next to a river or stream that can become inundated when the river or stream overflows.

A strip of relatively flat and normally dry land alongside a stream, river, or lake that is covered by water during a flood. See also Flood Insurance

the relatively flat area forming the valley floor on either side of a river channel, which is sometimes flooded 

low- and flat-lying areas adjacent to a river, containing river-transported sediment deposited during floods

A flood plain is low-lying land that's known to become submerged in water occasionally due to inclement weather and/or overflow of a nearby body of water.  

A relatively flat surface next to a stream. During floods, when the stream overflows its banks, water flows over the flood plain. Streams construct flood plains that accommodate their maximum flood ca [..]

A relatively flat surface next to a stream. During floods, when the stream overflows its banks, water flows over the flood plain. Streams construct flood plains that accommodate their maximum flood capacity.

A lowland adjoining a watercourse. At a minimum, the area is subject to a 1% or greater chance of flooding in a given year.

The nearly flat portion of a river (stream) valley adjacent to the river (stream) channel; it is built by sediment deposited during floods and is covered by water during a flood.

A strip of relatively flat and normally dry land alongside a stream, river, or lake that is covered by water during a flood.

In hydrologic terms, the portion of a river valley that has been inundated by the river during historic floods.

That portion of a river valley, adjacent to the river channel, which is built of sediments deposited by the river and which is covered with water when the river overflows its banks at flood stages.

The relatively flat area adjacent to a stream that is covered by water when the stream overflows its banks during a flood. The 100-year flood plain is defined as those areas near a stream that have a [..]

Low-lying area next to a river or the sea where water flows in times of flood, or would flow but for the presence of flood defences.

A generally flat area of land adjacent to a watercourse or sea where sea or water flows in time of flooding.

Level land that may be submerged by flood waters.

Level land that may be submerged by flood waters.

Level land that may be submerged by flood

In hydrologic terms, the portion of a river valley that has been inundated by the river during historic floods.

Level land that may be submerged by flood waters.

a lowland area near a river or stream that is subject to periodic flooding.