(1) The process of gravity separation of suspended matter carried by water, wastewater or other liquids, by gravity. It is usually accomplished by reducing the velocity of the liquid below the point at which it can transport the suspended material. Also called settling. May be enhanced by coagulation and flocculation. (2) In geology, sedimentation consists of five fundamental processes: weathering, erosion, transportation, deposition and diagnosis or consolidation into rock. (3) Solid-liquid separation resulting from the application of an external force, usually settling in a clarifier under the force of gravity. It can be variously classed as discrete, flocculent, hindered and zone sedimentation.

This definition is in context to Sanitation. See more contextual defintions for Sedimentation.