Etymologically
Log in

triangulum

This is the current revision of this entry, as edited by bogdan on 24 October 2026 at 18:46. This address is a permanent link to this version.
Changes in this edit History

Pronunciation

  • Classical: [triˈaŋ.ɡʊ.ɫũː][1]
  • Ecclesiastical: [triˈaŋ.ɡu.lum][1]

Forms

triangulum n (genitive triangulī); second declension[1]

Etymology

It is from Latin triangulus (“three-cornered, triangular”), the neuter of the adjective used as a noun.[2][3] The adjective is formed from tri- (“three”) and angulus (“corner, angle”).[2][4][3]

Earliest recorded meaning

It is found from Cicero on,[5] who uses the noun for a triangle in De natura deorum.[4][6]

Semantic evolution

The adjective triangulus described three-cornered things: a shape of skin in Celsus, a field in Columella and the outline of Sicily in Pliny the Elder.[4][7] In astronomy the neuter plural named stars standing a third of the zodiac apart, beside quadrata for those a quarter apart.[2][7] The land surveyors also used a masculine noun triangulus for the figure.[7][6]

Medieval geometry kept the noun and the adjective, as in Adelard's Elements.[8] It passed into French as triangle, and German Triangel and Middle High German drīangel go back to it.[1][5]

Timeline

  • 81–43 BC – Cicero uses the noun for a triangle and the adjective of stars in a trine aspect.[2][4][5]
  • 14–37 AD – Celsus uses the adjective of a three-cornered shape.[4][7][5]
  • 1st century AD – Columella speaks of a triangular field.[4][5]
  • 23/24–79 AD – Pliny the Elder uses both the noun and the adjective.[4][6][5]
  • c. 35–95/96 AD – Quintilian notes that squares enclose more space than triangles: quadrata amplius spatium complectuntur triangulis.[4][5]
  • late 14th century – English takes it over as triangle, partly through French.[3]

Meanings

Noun

  1. A triangle.[2][4][7]
  2. (astronomy, plural) Stars standing in a trine aspect, a third of the zodiac apart.[2][7]

Word family

  • triangulāris

References

  1. ^ a b c d Wiktionary, the free dictionary, https://en.wiktionary.org
  2. ^ a b c d e f Glare, P. G. W., ed. (2012), Oxford Latin Dictionary, 2nd ed., Oxford: Oxford University Press
  3. ^ a b c Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
  4. ^ a b c d e f g h i Lewis, Charlton T.; Short, Charles (1879), A Latin Dictionary, Oxford: Clarendon Press
  5. ^ a b c d e f g Köbler, Gerhard (2010), Lateinisches Abkunfts- und Wirkungswörterbuch für Altertum und Mittelalter, online ed., koeblergerhard.de
  6. ^ a b c Gaffiot, Félix (2016), Dictionnaire latin-français, new ed. by Gérard Gréco et al. (Gaffiot 2016), online ed.
  7. ^ a b c d e f Georges, Karl Ernst (1913–1918), Ausführliches lateinisch-deutsches Handwörterbuch, 8th ed., ed. Heinrich Georges, Hannover; Leipzig: Hahn
  8. ^ Latham, R. E., D. R. Howlett, R. K. Ashdowne, et al. (1975–2013), Dictionary of Medieval Latin from British Sources, London: British Academy / Oxford University Press