Merriam-Webster's Collegiate® Dictionary, 11th Edition
SILT
I. noun
Etymology: Middle English cylte, probably of Scandinavian origin; akin to Norwegian dialect sylt beach flooded at high tide; akin to Old High German sulza salt marsh, Old English sealt salt
Date: 15th century
loose sedimentary material with rock particles usually 1/20 millimeter or less in diameter, a deposit of sediment (as by a river), silty adjective
II. verb
Date: 1799
intransitive verb to become choked or obstructed with silt, transitive verb to choke, fill, cover, or obstruct with silt or mud , siltation noun