Main Entry: sludge

Pronunciation: \ˈsləj\

Function: noun

Etymology: Middle English slugge, perhaps alteration of slicche mud, slush; akin to Old High German slīh mire

Date: 15th century

1 : mud, mire; especially : a muddy deposit (as on a riverbed) : ooze
2 : a muddy or slushy mass, deposit, or sediment: as a : precipitated solid matter produced by water and sewage treatment processes b : muddy sediment in a steam boiler c : a precipitate or settling (as a mixture of impurities and acid) from a mineral oil
3 : slush 5

— sludgy \ˈslə-jē\ adjective