Etymologically
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sludge

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Pronunciation

Etymology

Its origin is uncertain.[2][3][4][5] The OED takes it as a variant of slutch, mud, mire,[6][4][3][7] a word recorded from about 1400 and itself of uncertain, perhaps imitative or expressive origin;[6] the American Heritage Dictionary likewise suggests an alteration of dialect slutch.[8] Others take it as a variant or alteration of slush.[9][3][10][11] Barnhart notes that other words for mud, slitch (about 1400) and sleech (1587), may also lie behind it,[3] and Dictionary.com derives the dialect forms from slich (“slime, wet mud”).[7][12] Klein gives sluche and compares dialect slud, mud.[13] Johnson supposed it to come from slough.[14]

Earliest recorded meaning

Mud, mire or ooze covering the ground or lying at the bottom of rivers: 1649, in W. Blith's English Improver.[6][3] Etymonline gives the 1640s,[4] and Merriam-Webster dates the first sense to the 15th century.[9]

Semantic evolution

Johnson (1755) defined it as mire, dirt mixed with water.[14] Hoad dates the sense "matter mixed with water or slime" to the 18th century.[11] The OED follows the word into industry: any earthy or slimy deposit (1702, in Savery's Miners Friend), finely crushed ore mixed with water in metallurgy (1757), the sediment in boilers (1839), the precipitate in sewage tanks (1877), a waste product of petroleum refining (1885), the thick deposit that forms in heated oil (1920), and in medicine sludged blood (1947).[6] Sailors used it from 1817 for ice imperfectly formed or broken into small pieces.[6][10] James Joyce used it figuratively in 1906 for a shapeless, undifferentiated mass,[6] and since 1962 it has also been the colour of sludge.[6] The verb, from 1757, meant to turn into sludge, later to clear of sludge, and since 1908 also to trudge.[6] In dialect from Scotland and Ireland to the Midlands it means wet mud or slush.[15]

Timeline

  • 1649 – mud, mire, ooze.[6][3]
  • 1702 – any earthy or slimy deposit.[6]
  • 1757 – metallurgy, crushed ore mixed with water; verb, to convert into sludge.[6]
  • 1817 – nautical, ice broken into small pieces.[6]
  • 1839 – sediment in boilers.[6]
  • 1877 – the precipitate in sewage tanks.[6]
  • 1885 – waste from petroleum refining.[6]
  • 1906 – figurative, a shapeless mass.[6]
  • 1908 – verb, to trudge.[6]
  • 1920 – a thick deposit in oil.[6]
  • 1947 – medicine, sludged blood.[6]
  • 1962 – the colour of sludge.[6]

Meanings

Noun

  1. Soft, thick, wet mud or mire; ooze.[10][9][6]
  2. A muddy or slimy sediment or deposit, as in a boiler, a tank or engine oil.[10][9][6]
  3. The solid matter that settles out in the treatment of sewage.[10][9][6]
  4. Broken or newly forming sea ice with a slushy look.[10][6]

Verb

  1. To turn into sludge, or to form sludge.[9][6]
  2. To clear of sludge.[9][6]

Word family

  • sludgy
  • activated sludge
  • slush
  • slutch
  • sleech
  • slitch
  • slough

References

  1. ^ Wiktionary, the free dictionary, https://en.wiktionary.org
  2. ^ Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
  3. ^ a b c d e f Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
  4. ^ a b c Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
  5. ^ Stevenson, Angus, ed. (2010), Oxford Dictionary of English, 3rd ed., Oxford: Oxford University Press
  6. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
  7. ^ a b Dictionary.com Unabridged (2016), based on the Random House Unabridged Dictionary, New York: Random House
  8. ^ The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
  9. ^ a b c d e f g Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
  10. ^ a b c d e f Collins English Dictionary (2023), Glasgow: HarperCollins
  11. ^ a b Hoad, T. F., ed. (1986), The Concise Oxford Dictionary of English Etymology, Oxford: Clarendon Press
  12. ^ Kurath, Hans; Kuhn, Sherman M.; Lewis, Robert E., eds. (1952–2001), Middle English Dictionary, Ann Arbor: University of Michigan Press; online edition ed. Frances McSparran et al. (2000–2018)
  13. ^ Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
  14. ^ a b Johnson, Samuel (1755), A Dictionary of the English Language, London; 4th ed. 1773; Johnson's Dictionary Online, ed. Beth Rapp Young et al.
  15. ^ Wright, Joseph, ed. (1898–1905), The English Dialect Dictionary, 6 vols., Oxford: Henry Frowde; via EDD Online 4.0, University of Innsbruck (CC BY 4.0)