D defs.my
Entry 4 senses Webster, 1913

Sludge

/slŭj/ · IPA /slʌd͡ʒ/
01 n. Mud; mire; soft mud; slush.
  1. 1.
    Mud; mire; soft mud; slush.
  2. 2.
    Small floating pieces of ice, or masses of saturated snow.
  3. 3.
    See Slime, 4.(Mining) See: Slime
  4. 4.
    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.
Phrases & compounds
Sludge hole — the hand-hole, or manhole, in a steam boiler, by means of which sediment can be removed.