A flood plain is a flat area of land near a river or stream that is prone to flooding. There are several synonyms that can be used to describe this type of terrain, including alluvial plain, floodway, and embayment. The terms flood zone, inundation area, and lowland are also commonly used to refer to areas that are susceptible to flooding. Other words that might be used to describe a flood plain include flood-prone, flood-prone area, and flood zone. Whether you're a scientist recording data about a river's behavior or a writer looking for descriptive language, these synonyms can help you communicate more effectively.