1. the erosion of soil or rock by rainwater
Usage: geological

Examples

• The hillside showed clear signs of rainwash after the heavy storms.
• Rainwash had carved deep channels in the exposed clay.
• The geologist studied the effects of rainwash on the canyon walls.
• Years of rainwash had gradually worn away the topsoil.
• The farmer planted cover crops to prevent rainwash on the slopes.