Meaning of SLUDGE in English
noun ·see slime, 4.
2. sludge ·noun mud; mire; soft mud; slush.
3. sludge ·noun small floating pieces of ice, or masses of saturated snow.
4. sludge ·add. ·noun anything resembling mud or slush; as: (a) a muddy or slimy deposit from sweage. (b) mud from a drill hole in boring. (c) muddy sediment in a steam boiler. (d) settling of cottonseed oil, used in making soap, ·etc. (e) a residuum of crude paraffin-oil distillation.
Webster English vocab. Английский словарь Webster. 2012