diagonalis

Forms

diagōnālis (neuter diagōnāle); third-declension two-termination adjective^[1]

Etymology

It is formed from Latin diagōnios + -ālis, from the Greek-derived adjective with the Latin suffix -ālis.^[2][3][1] diagōnios is from Ancient Greek διαγώνιος (diagṓnios, “from angle to angle”),^[1][4] made of διά (diá, “through, across”) and γωνία (gōnía, “angle, corner”).^[5][6][4] The TLL also compares the form diagōnus.^[7]

Earliest recorded meaning

The first author to use it is Vitruvius, who speaks of the length of a diagonal line in a geometrical figure.^[3][7][6]

Semantic evolution

In Classical and Late Latin it belongs to geometry and land surveying: the Roman surveyors use it of boundary lines (limites) drawn across a square, and once as a noun for a line running from south to north across a circle.^[7][5] The OLD treats it as a synonym of diagōnios.^[2]

Medieval writers kept the geometrical sense, both as an adjective and as a noun for a diagonal line.^[8] Italian diagonale continues it,^[9] and it reached English through Old French as diagonal.^[4]

Timeline

• c. 84–c. 25 BC – Vitruvius speaks of a diagonal line.^[3][7][6]
• 5th century AD – The surveyors' writings use it of boundary lines.^[6][7]
• 1177–1217 – Alexander Neckam describes a square drawn on a diagonal line.^[8]
• early 15th century – English has diagonal, from Old French.^[4]

Meanings

Adjective

1. Diagonal, running from one angle of a figure to another.^[2][3][7]
2. (as a noun) A diagonal line.^[5][8]

Related words

• diagōnios
• English diagonal

References

1. ^ a b c d e Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c Glare, P. G. W., ed. (2012), Oxford Latin Dictionary, 2nd ed., Oxford: Oxford University Press
3. ^ a b c d Lewis, Charlton T.; Short, Charles (1879), A Latin Dictionary, Oxford: Clarendon Press
4. ^ a b c d Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
5. ^ a b c Georges, Karl Ernst (1913–1918), Ausführliches lateinisch-deutsches Handwörterbuch, 8th ed., ed. Heinrich Georges, Hannover; Leipzig: Hahn
6. ^ a b c d Köbler, Gerhard (2010), Lateinisches Abkunfts- und Wirkungswörterbuch für Altertum und Mittelalter, online ed., koeblergerhard.de
7. ^ a b c d e f Thesaurus linguae Latinae (1900–), Leipzig: Teubner; Berlin: De Gruyter; open-access ed., Munich: Bayerische Akademie der Wissenschaften
8. ^ a b c 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
9. ^ Conte, Gian Biagio; Pianezzola, Emilio; Ranucci, Giuliano (2010), il Latino: Vocabolario della lingua latina, 3rd ed., Florence: Le Monnier