A piece of ground washed by the action of a sea or river, or sometimes covered and sometimes left dry; the shallowest part of a river, or arm of the sea; also, a bog; a marsh; a fen; as, the washes in Lincolnshire.
Substances collected and deposited by the action of water; as, the wash of a sewer, of a river, etc.
form by erosion; "The river washed a ravine into the mountainside"
a small river or stream
wash is a natural rainwater run off channel. A wash is smaller than a ravine.