Etymologically
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infidelity

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Pronunciation

  • /ˌɪnfɪˈdɛlɪti/[1]

Etymology

It is inherited from Middle English infidelite,[2] borrowed from Old French infidelité[2][3][4][5] and directly borrowed from Latin infidēlitās (“unfaithfulness, faithlessness”),[3][4][6][7] from infidēlis (“unfaithful, unbelieving”) and the suffix -tās.[4][7] The Latin adjective, the source of infidel, is formed from in- (“not”) and fidēlis (“faithful”).[3] In Old French the word is recorded about 1170, of the Christian faith,[4] and in post-classical Latin it meant lack of religious faith from the 4th century and treachery from the 7th.[4] The OED compares infedeltà and infidelidad.[4] Merriam-Webster gives the source as Middle French infidelité.[8]

Earliest recorded meaning

False belief, unbelief in the Christian faith, and disloyalty: all three senses are in the Middle English Dictionary's quotations from the first half of the 15th century, the earliest in a translation of Higden.[2] Etymonline dates the word to about 1400,[3] Dictionary.com to 1375–1425,[7] and the OED, whose entry has not been fully revised, to 1509, in Barclay's Shyp of Folys.[4]

Semantic evolution

In Middle English the word belonged mainly to religion, for paganism or lack of faith;[2][3] from the late 16th century it was also used of the beliefs of other religions, especially Islam, a sense obsolete by about 1700.[4] The sense of disloyalty to a person was first used of a sovereign, lord or master,[3][4] and in the 16th century also of a lover or spouse,[3] which is the main sense today.[4][5] An infidelity, a single unfaithful act, is recorded from 1714, in the Spectator.[4] Johnson (1755) defined it first as want of faith and then as disbelief of Christianity.[9] The general sense of disbelief or incredulity, from 1578, is now archaic,[4][8] and Merriam-Webster also records a failure to copy something exactly.[8]

Timeline

  • c. 1425 – false belief, lack of faith, and disloyalty.[2]
  • 1509 – unbelief in religious matters, especially in Christianity.[4]
  • 1529 – unfaithfulness or disloyalty to a person.[4]
  • 1578 – disbelief, incredulity in general.[4]
  • 1597 – the beliefs of a religion other than Christianity (obsolete by 1700).[4]
  • 1714 – an act of unfaithfulness.[4]

Meanings

Noun

  1. Romantic or sexual unfaithfulness to one's husband, wife or partner, or a single act of it: The marriage did not survive his infidelity.[8][10][4]
  2. Disloyalty; a breach of trust or of a duty.[8][10][4]
  3. Lack of religious faith, especially in Christianity.[8][10][4][5]
  4. A failure to reproduce something, such as a text, exactly.[8]
  5. (archaic) Disbelief or incredulity in general.[8][4][5]

References

  1. ^ Wiktionary, the free dictionary, https://en.wiktionary.org
  2. ^ a b c d e 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)
  3. ^ a b c d e f g Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
  4. ^ a b c d e f g h i j k l m n o p q r s t u Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
  5. ^ a b c d Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
  6. ^ Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
  7. ^ a b c Dictionary.com Unabridged (2016), based on the Random House Unabridged Dictionary, New York: Random House
  8. ^ a b c d e f g h Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
  9. ^ Johnson, Samuel (1755), A Dictionary of the English Language, London; 4th ed. 1773; Johnson's Dictionary Online, ed. Beth Rapp Young et al.
  10. ^ a b c Collins English Dictionary (2023), Glasgow: HarperCollins