a level or gently sloping surface formed of sediments laid down by streams, generally during flooding.
These Plain Words Have Very Odd Origin StoriesOver the years, these words have gone on a journey from signifying creepy, strange, antithetical, and even paranormal ideas to taking on the standard meanings we know and understand today.
Origin of alluvial plain
First recorded in 1955–60
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019