sludge

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Semisolid material such as the type precipitated by sewage treatment.
• noun Mud, mire, or ooze covering the ground or forming a deposit, as on a riverbed.
• noun Finely broken or half-formed ice on a body of water, especially the sea.
• noun An agglutination or aggregation of blood cells forming a semisolid mass that often impedes circulation.
• intransitive verb To agglutinate or aggregate into a semisolid mass; form a sludge. Used of blood cells.

from The Century Dictionary.

• noun The more or less viscid mud thrown down from dilute waste soap-liquors of wool-scouring, cotton-bleaching, and dyeing industries when such liquors are treated with crude aluminium sulphate and milk of lime. The remaining effluent is thus in a large measure purified, but the sludge thrown down has usually little value, even as a manure.
• noun The precipitated solid matter in sewage, usually collected in settling-basins in sewage-disposal works after chemical treatment and filtration. Often pressed into cakes.
• noun The sediment, in the form of a mud, which collects in a steam-boiler.
• noun Incorrectly, by abbreviation, an opening in a steam-boiler for the removal of sludge or mud; also, the lid which covers such an opening.
• noun A sand-pump or mud-pumping device for removing sludge from a sink or a bore-hole.
• noun The silt-like deposit in the bottom of an electrolytic cell.
• noun Mud; mire.
• noun A pasty mixture of snow or ice and water; half-melted snow; slush.
• noun In mining, the fine powder produced by the action of the drill or borer in a bore-hole, when mixed with water, as is usually the case in large and deep bore-holes. The powder when dry is often called bore-meal.
• noun Refuse from various operations, as from the washing of coal; also, refuse acid and alkali solutions from the agitators, in the refining of crude petroleum: sometimes used, but incorrectly, as the equivalent of slimes, or the very finely comminuted material coming from the stamps. See Slime, 3.

from the GNU version of the Collaborative International Dictionary of English.

• noun Mud; mire; soft mud; slush.
• noun Small floating pieces of ice, or masses of saturated snow.
• noun (Mining) See Slime, 4.
• 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.
• noun the hand-hole, or manhole, in a steam boiler, by means of which sediment can be removed.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A generic term for solids separated from suspension in a liquid.
• noun A residual semi-solid material left from industrial, water treatment, or wastewater treatment processes.
• noun A sediment of accumulated minerals in a steam boiler.
• noun A mass of small pieces of ice on the surface of a body of water.
• verb intransitive, informal to slump or slouch.
• verb intransitive to slop or drip slowly.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the precipitate produced by sewage treatment
• noun any thick, viscous matter