sludge

Possibly related to slush.

• IPA^(key): /slʌd͡ʒ/

• Audio (Southern England):

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• Audio (US):

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• Rhymes: -ʌd͡ʒ

sludge (countable and uncountable, plural sludges)

1. Solids separated from suspension in a liquid.
   • 2013 June 29, “High and wet”, in The Economist, volume 407, number 8842, page 28:

     Floods in northern India, mostly in the small state of Uttarakhand, have wrought disaster on an enormous scale. […] Rock-filled torrents smashed vehicles and homes, burying victims under rubble and sludge.

2. A residual semi-solid material left from industrial, water treatment, or wastewater treatment processes.
3. A sediment of accumulated minerals in a steam boiler.
4. A mass of small pieces of ice on the surface of a water body.
5. (uncountable, music) Ellipsis of sludge metal.
6. (behavioral science) Institutional policies that introduce tedium and inefficiency in processes.
   • [2025 June 29, Chris Colin, “That Dropped Call With Customer Service? It Was on Purpose.”, in The Atlantic‎^[1], retrieved 29 June 2025, Ideas:

     In the 2008 best seller Nudge, the legal scholar Cass R. Sunstein and the economist Richard H. Thaler marshaled behavioral-science research to show how small tweaks could help us make better choices. An updated version of the book includes a section on what they called “sludge”—tortuous administrative demands, endless wait times, and excessive procedural fuss that impede us in our lives.]

• (separated solids): mire, mud, ooze, slush

sludge (third-person singular simple present sludges, present participle sludging, simple past and past participle sludged)

1. (intransitive, informal) To slump or slouch.
2. (intransitive) To slop or drip slowly.