Etymologically
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convex

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Pronunciation

  • UK: /ˈkɒn.vɛks/, /kɒnˈvɛks/[1]
  • US: /ˈkɑn.vɛks/, /kɑnˈvɛks/[1]

Etymology

It is borrowed from Latin convexus (“vaulted, arched, rounded”),[2][3][4][5][6][7] which Barnhart, Etymonline and Klein see as coming through Middle French convexe;[8][9][10] Merriam-Webster gives the source as either.[11] The origin of the Latin word is disputed.[7][10] The OED, Etymonline and Ayto take it as an old past participle of convehō (“to bring together”), from com- (“together”) and vehō (“to carry”), because the ends of an arch are brought together to meet at the top;[2][9][7][12] Etymonline traces vehō to Proto-Indo-European *wegh- (“to go, transport in a vehicle”).[9][3] Klein, Skeat, Barnhart and Merriam-Webster instead connect -vexus with a root meaning "to bend, be curved", found also in vacillō (“to sway, waver”) and Old English wōh (“crooked”).[10][13][8][11] The OED notes that Latin convexus could also include the sense "concave".[2]

Earliest recorded meaning

Curved like the outside of a circle or sphere, and of glasses and mirrors of that shape: in L. Digges's Pantometria, published in 1571,[2][8][11] which the OED dates to possibly before 1560.[2]

Semantic evolution

The word came into English in geometry and optics, with convex lenses and mirrors among its first uses.[2] In the 17th century it was also a noun for a convex surface or vault, and poets used it for the vault of the sky or of hell (1627–1715);[2][11] Milton stressed the second syllable.[2] Johnson (1755) defined it as "rising in a circular form; opposite to concave".[14] Later senses are a convex lens (1705), a card cut slightly convex for cheating (1864), and in mathematics a figure or set that contains the straight line joining any two of its points (1858).[2] Etymonline dates the phrase convex lens to 1822.[9] The verb, to bend outwards, is recorded from 1805.[2]

Timeline

  • 1571 – curved like the outside of a sphere; of lenses and mirrors.[2][8][11]
  • 1626 – noun, a convex surface or vault (obsolete by 1796).[2]
  • 1627 – noun, in poetry, the vault of the sky (obsolete by 1715).[2]
  • 1705 – noun, a convex lens.[2]
  • 1805 – verb, to bend outwards.[2]
  • 1822 – convex lens.[9]
  • 1858 – in mathematics, of a figure or set.[2]
  • 1864 – a card cut convex for cheating.[2]

Meanings

Adjective

  1. Curving or bulging outwards, like the outside of a circle or sphere; the opposite of concave: a convex mirror at the corner of the street.[15][11][2]
  2. (physics) Of a lens, having one or both surfaces curved outwards.[15][2]
  3. (mathematics) Of a polygon, having no interior angle greater than 180 degrees; of a set, containing the straight line between any two of its points; of a function, having a graph that bends upwards.[15][2][11]

Noun

  1. (archaic) A convex surface or body, especially a vault or the vault of the sky seen from outside.[11][2]

Verb

  1. To make convex, or to bend outwards.[15][11][2]

Word family

  • convexly
  • convexedness
  • biconvex
  • concavo-convex
  • convexity
  • plano-convex
  • subconvex
  • convex hull

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 Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
  3. ^ a b The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
  4. ^ Stevenson, Angus, ed. (2010), Oxford Dictionary of English, 3rd ed., Oxford: Oxford University Press
  5. ^ Hoad, T. F., ed. (1986), The Concise Oxford Dictionary of English Etymology, Oxford: Clarendon Press
  6. ^ Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
  7. ^ a b c Ayto, John (2005), Word Origins: The Secret Histories of English Words from A to Z, 2nd ed., London: A & C Black
  8. ^ a b c d Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
  9. ^ a b c d e Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
  10. ^ a b c Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
  11. ^ a b c d e f g h i Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
  12. ^ Weekley, Ernest (1921), An Etymological Dictionary of Modern English, London: John Murray
  13. ^ Skeat, Walter W. (1911), A Concise Etymological Dictionary of the English Language, new ed., Oxford: Clarendon Press
  14. ^ Johnson, Samuel (1755), A Dictionary of the English Language, London; 4th ed. 1773; Johnson's Dictionary Online, ed. Beth Rapp Young et al.
  15. ^ a b c d Collins English Dictionary (2023), Glasgow: HarperCollins