Etymologically
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triad

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Pronunciation

  • /ˈtɹaɪ.æd/[1]

Etymology

It is borrowed from Late Latin trias (“the number three, a triad”),[2][3][4][5][6] from Ancient Greek τριάς (triás, “the number three, a group of three”),[4][7][5] from τρεῖς (treîs, “three”),[3][4][7] which is related to three.[4][8] Hoad, the Shorter Oxford and the Oxford Dictionary of English allow a borrowing from French triade as well,[9][10][11] which the OED dates in French to 1564.[5]

Earliest recorded meaning

A group or set of three: 1546, in the State Papers of Henry VIII.[5][3] Etymonline dates the word to the 1540s, in the sense of a union or conjunction of three.[4]

Semantic evolution

Johnson (1755) gave only "three united".[12] From the 17th century the general sense was applied to particular groups: the number three in Pythagorean philosophy (1660), the Trinity (1661), after the Greek use of triás by early Christian writers, and a group of three gods or powers (before 1746).[5] Scholars of Welsh literature used it from 1839 for a form of composition that arranges subjects or statements in threes.[5] Technical senses followed: in music a chord of a note with its third and fifth, recorded from 1786 in the OED,[5] while Etymonline dates it to 1801;[4] in chemistry a trivalent element (1865); and in pathology a group of three symptoms (1899).[5] From 1821 English used Triad Society for a Chinese secret society, translating its Chinese name, San Ho Hui, literally "three unite society", said to mean the union of Heaven, Earth and Man.[5][11] Collins records the later sense of the American nuclear force of land-based missiles, submarine-launched missiles and bombers.[13]

Timeline

  • 1546 – a group or set of three.[5][3]
  • 1660 – the number three, in Pythagorean philosophy.[5]
  • 1661 – the Trinity.[5]
  • before 1746 – a group of three deities or powers.[5]
  • 1786 – in music, a chord of three notes.[5] Etymonline dates this sense to 1801.[4]
  • 1821 – the Triad Society, a Chinese secret society.[5]
  • 1839 – a Welsh literary form arranged in threes.[5]
  • 1865 – in chemistry, a trivalent element or radical.[5]
  • 1899 – in pathology, a group of three symptoms.[5]

Meanings

Noun

  1. A group of three closely related people, things or ideas; a trio: a triad of virtues.[13][8][5]
  2. In music, a chord of three notes, a root with the third and fifth above it.[13][8][5]
  3. In chemistry, a trivalent atom, element or radical.[13][8][5]
  4. A short aphoristic form of medieval Welsh and Irish literature, grouping its statements in threes.[13][8][5]
  5. In medicine, a set of three symptoms or signs that occur together.[8][5]
  6. The United States' strategic nuclear force of intercontinental ballistic missiles, submarine-launched missiles and bombers.[13]
  7. Triad: any of several Chinese secret societies, especially one engaged in organized crime.[13][5][11]

Word family

  • triadic
  • triadically
  • triadism
  • major triad
  • minor triad

References

  1. ^ Wiktionary, the free dictionary, https://en.wiktionary.org
  2. ^ Barnhart, Robert K., ed. (1995), The Barnhart Concise Dictionary of Etymology, New York: HarperCollins
  3. ^ a b c d Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
  4. ^ a b c d e f g Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
  5. ^ a b c d e f g h i j k l m n o p q r s t u v w x Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
  6. ^ The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
  7. ^ a b Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
  8. ^ a b c d e f Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
  9. ^ Hoad, T. F., ed. (1986), The Concise Oxford Dictionary of English Etymology, Oxford: Clarendon Press
  10. ^ Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
  11. ^ a b c Stevenson, Angus, ed. (2010), Oxford Dictionary of English, 3rd ed., Oxford: Oxford University Press
  12. ^ Johnson, Samuel (1755), A Dictionary of the English Language, London; 4th ed. 1773; Johnson's Dictionary Online, ed. Beth Rapp Young et al.
  13. ^ a b c d e f g Collins English Dictionary (2023), Glasgow: HarperCollins