sediment /ˈsɛd.ɪ.mənt/verb 2noun 1forms 3 verb2 •To deposit material as a sediment. •To be deposited as a sediment. noun1 •A collection of small particles, particularly dirt, that precipitates from a river or other body of water.The Nile delta is composed of sediment that was washed down and deposited at the mouth of the river. formssedimented · sedimenting · sediments