SLUDGE

noun Etymology: Middle English slugge, perhaps alteration of slicche mud, slush; akin to Old High German slīh mire Date: 15th century mud , mire , a muddy or slushy mass, deposit, or sediment: as, precipitated solid matter produced by water and sewage treatment processes, muddy sediment in a steam boiler, a precipitate or settling (as a mixture of impurities and acid) from a mineral oil, slush 5, sludgy adjective