Etymologically
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incest

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Pronunciation

  • /ˈɪn.sɛst/[1]

Etymology

It is inherited from Middle English incest,[2] borrowed from Latin incestus (“unchastity, incest”) or incestum, both nouns formed from the adjective incestus, impure, unchaste.[3][4][5][6] The adjective is formed from in- (“not”) and castus (“pure, chaste”), the source of chaste,[3][7][8] which the American Heritage Dictionary traces to Proto-Indo-European *kes-.[4] Klein takes the second part instead as the Old Latin noun castus, chastity, which is related to the adjective.[9] Barnhart and Etymonline see it as coming partly through Old French inceste (“incest; lechery, fornication”),[10][11] but the OED records the French word only from the 14th century.[3] Old English had sibleger (“incest”), literally "kin-lying".[11][12]

Earliest recorded meaning

Sexual intercourse between persons too closely related to marry: first recorded about 1225, in the Ancrene Riwle,[3][10] which Barnhart dates to probably before 1200.[10] Etymonline dates the word to about 1200.[11]

Semantic evolution

Ayto notes that the Latin word meant unchastity in general, but was in practice often used of sex between close relatives,[7] and the Old French word could also mean lechery or fornication.[11] In English the first records already have the narrow sense, and the same early text it also appears in spiritual incest, a term of the Roman Catholic Church for a sexual relation between people joined by a spiritual bond or involving someone under a vow.[3] Chaucer used the noun.[13] From 1484, in Caxton's translation of Aesop, incest could also name a person guilty of incest, a sense now obsolete.[3][14] The adjective incestuous followed in 1532, in Sir Thomas More.[10][8] Johnson (1755) defined incest as a criminal union of persons within the prohibited degrees, quoting Measure for Measure.[15] In law it is now specifically the crime of intercourse between parent and child or grandchild, or between brothers and sisters.[5]

Timeline

  • c. 1225 – sexual intercourse between near relatives, and spiritual incest, in the Ancrene Riwle.[3]
  • 1484 – a person guilty of incest (now obsolete).[3][14]
  • 1532 – the adjective incestuous, in Thomas More.[10]

Meanings

Noun

  1. Sexual intercourse between people so closely related that they are not allowed to marry: The novel deals frankly with incest in a remote village.[16][6][3]
  2. (law) The crime of sexual intercourse between a parent and a child or grandchild, or between brothers and sisters or half-siblings.[5][3]

Word family

  • incestuous
  • chaste
  • caste
  • castigate
  • unchaste

References

  1. ^ Wiktionary, the free dictionary, https://en.wiktionary.org
  2. ^ Stratmann, Francis Henry (1891), A Middle-English Dictionary, revised by Henry Bradley, Oxford: Clarendon Press
  3. ^ a b c d e f g h i j Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
  4. ^ a b The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
  5. ^ a b c Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
  6. ^ a b Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
  7. ^ a b Ayto, John (2005), Word Origins: The Secret Histories of English Words from A to Z, 2nd ed., London: A & C Black
  8. ^ a b Hoad, T. F., ed. (1986), The Concise Oxford Dictionary of English Etymology, Oxford: Clarendon Press
  9. ^ Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
  10. ^ a b c d e Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
  11. ^ a b c d Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
  12. ^ Bosworth, Joseph; Toller, T. Northcote (1898), An Anglo-Saxon Dictionary, Oxford: Clarendon Press; Toller, T. Northcote (1921), Supplement
  13. ^ Skeat, W. W., ed. (1894), The Complete Works of Geoffrey Chaucer, vol. VI: Glossarial Index, Oxford: Clarendon Press
  14. ^ a b Kay, Christian; Roberts, Jane; Samuels, Michael; Wotherspoon, Irené, eds. (2009), Historical Thesaurus of the Oxford English Dictionary, Oxford: Oxford University Press; online edition (2024)
  15. ^ Johnson, Samuel (1755), A Dictionary of the English Language, London; 4th ed. 1773; Johnson's Dictionary Online, ed. Beth Rapp Young et al.
  16. ^ Collins English Dictionary (2023), Glasgow: HarperCollins