(1) In a biological context: organic particulate matter. (ISO/6107)
(2) In the context of sewage treatment practice: coarse debris denser than water but capable of being transported in moving water. (ISO/6107)
(3) Any accumulation of loose material arising from the waste of rocks. It may occur in the place where it is produced, or it may be transported by streams or ice and deposited in other localities.
UNESCO/WMO International Glossary of Hydrology (2nd revised ed., 1992)