- mud, mire, or ooze covering the ground or forming a deposit at the bottom of bodies of water
- spongy lumps of drift ice
- any heavy, slimy deposit, sediment, or mass, as the waste resulting from oil refining, the mud brought up by a mining drill, the precipitate in a sewage tank, the sediment in a steam boiler or crankcase, etc.
var. of slutch, sludge, mud: akin to ME sluchched, muddy, prob. ult. < IE base *(s)leu-, to hang limply > sleet, MHG slote, mud, ooze