Etymologically
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perpendicular

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Pronunciation

  • UK: /ˌpɜː.pənˈdɪk.jə.lə(ɹ)/[1]
  • US: /ˌpɝ.pənˈdɪk.ju.lɚ/, /ˌpɝ.pənˈdɪk.jə.lɚ/[1]

Etymology

It is inherited from Middle English perpendiculer,[2][3][4] borrowed from Middle French perpendiculer, modern perpendiculaire, and its source borrowed from Latin perpendiculāris (“vertical, as a plumb line; at right angles”),[2][3][5] from perpendiculum (“plumb line, plummet”),[2][6][5][7] from perpendō (“to weigh carefully”),[6][3][5] formed from per- (“thoroughly”) and pendō (“to weigh, to hang”),[6][3][5] which Etymonline traces to Proto-Indo-European *(s)pen- (“to draw, stretch, spin”).[5] Merriam-Webster and the ODE instead take the second part as pendeō (“to hang”).[4][8] Etymonline and Barnhart call the French form Old French,[5][3] and Etymonline calls the Latin adjective Late Latin.[5] The modern spelling, which follows the Latin, appears by 1555.[3] The OED compares perpendicular, perpendicular and perpendicolare.[2]

Earliest recorded meaning

At right angles to the horizon, vertical: in Chaucer's Treatise on the Astrolabe (1391), where Barnhart reads the word as an adverb;[2][3][5] the adjective follows about 1475.[3][5]

Semantic evolution

The word began in astronomy, of a line at right angles to the plane of the horizon.[5][9] About 1475 it was used of a line or plane at right angles to another line or surface, and this became the main sense in geometry and engineering.[2] Hoad notes that it was not in general use until the 16th century.[7] The noun, a line at right angles to another, appears in Robert Recorde's Pathway to Knowledge (1551);[2][4] Etymonline notes that the earlier noun was perpendicle.[5] The loosened sense "very steep" is first found in Shakespeare's Henry IV, Part 1 (1598).[2][10] From 1768, in Sterne, it described a person standing upright,[2] and in 1817 Thomas Rickman applied it to the last style of English Gothic architecture, with its strong vertical lines.[2][9][7] From 1555 to 1693 the word could also be used figuratively for "directly dependent".[2] In 19th-century university slang a perpendicular was a party or meal at which the guests stood,[2] and in slang it has also meant sexual intercourse standing up.[11]

Timeline

  • 1391 – at right angles to the horizon, vertical.[2][3]
  • c. 1475 – of a line or plane, at right angles to another line or surface.[2][3]
  • 1551 – noun, a straight line at right angles to another.[2][4]
  • 1555 – spelling with -ar; figuratively, directly dependent (obsolete by 1693).[3][2]
  • 1598 – very steep, precipitous.[2][10]
  • 1604 – noun, a plumb line or similar instrument (obsolete by 1859).[2]
  • 1768 – of a person, upright, standing.[2]
  • 1817 – the Perpendicular style of English Gothic architecture.[2]
  • 1863 – university slang, a party or meal eaten standing (obsolete).[2]

Meanings

Adjective

  1. At right angles to a given line or plane: Draw a line perpendicular to the base.[12][4][2]
  2. Exactly vertical or upright; at right angles to the horizon.[12][4][2]
  3. Very steep; nearly vertical: a perpendicular cliff.[2][4]
  4. Architecture, usually Perpendicular: of the last style of English Gothic architecture, of the 14th and 15th centuries, with strongly vertical tracery and fan vaulting.[12][2]

Noun

  1. A line at right angles to another line or plane.[4][2]
  2. the perpendicular: an exactly vertical line or position.[2][4]
  3. (obsolete, 1604–1859) An instrument showing the vertical, such as a plumb line.[2][4]

Word family

  • perpendicularity
  • perpendicularly
  • nonperpendicular

References

  1. ^ a b Wiktionary, the free dictionary, https://en.wiktionary.org
  2. ^ 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 27 28 Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
  3. ^ a b c d e f g h i j k Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
  4. ^ a b c d e f g h i j Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
  5. ^ a b c d e f g h i j k Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
  6. ^ a b c The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
  7. ^ a b c Hoad, T. F., ed. (1986), The Concise Oxford Dictionary of English Etymology, Oxford: Clarendon Press
  8. ^ Stevenson, Angus, ed. (2010), Oxford Dictionary of English, 3rd ed., Oxford: Oxford University Press
  9. ^ a b Weekley, Ernest (1921), An Etymological Dictionary of Modern English, London: John Murray
  10. ^ a b Cresswell, Julia (2021), Oxford Dictionary of Word Origins, 3rd ed., Oxford: Oxford University Press
  11. ^ Green, Jonathon (2010), Green's Dictionary of Slang, London: Chambers; digital ed. 2016–, https://greensdictofslang.com
  12. ^ a b c Collins English Dictionary (2023), Glasgow: HarperCollins