\Sludge\, n.
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.

\Sludge\, n. [CF. {Slush}.]
1. Mud; mire; soft mud; slush. --Mortimer. Tennyson.
2. Small floating pieces of ice, or masses of saturated snow.
   --Kane.
3. (Mining) See {Slime}, 4.
{Sludge hole}, the hand-hole, or manhole, in a steam boiler,
   by means of which sediment can be removed.