perpendiculum

Forms

perpendiculum n (genitive perpendiculī); second declension^[1] A masculine perpendiculus occurs in Frontinus' writings on land surveying.^[2][3]

Etymology

It is from Latin perpendō (“to weigh carefully”) + -culum, a noun of instrument.^[2][1][3] De Vaan lists it among the derivatives of pendō (“to hang, weigh”), which goes back to Proto-Italic *pend-e/o- (“to hang”) and Proto-Indo-European *(s)pend-e/o- (“to spin”).^[4] Isidore of Seville explains it as what always hangs down.^[3]

Earliest recorded meaning

De Vaan records it first in Cato,^[4][5] who prescribes in De agri cultura that a small post should stand upright in the middle ad perpendiculum, “vertically”.^[2]

Semantic evolution

It names the plumb line: Cicero speaks of testing columns by the plumb line, and of using plumb line and cord;^[2][6] Vitruvius, Pliny the Elder and Apuleius use it in building and in measuring heights.^[2][6] From the instrument it came to mean the vertical line or plane itself, as in Vitruvius.^[2] The phrase ad perpendiculum, “vertically”, is the commonest use, as in Cicero's De fato of bodies falling by their weight and in Caesar of timbers not set vertically but slanting.^[2] Ausonius uses it figuratively of someone who kept himself and his family strictly in line.^[7] Medieval writers in Britain use it for the plumb line, a mason's rule, the perpendicular, and a pothook.^[8]

Timeline

• 234–149 BC – Cato uses ad perpendiculum for “vertically”.^[2][4][5]
• 81–43 BC – Cicero uses it of the plumb line.^[2][5]
• c. 84–c. 25 BC – Vitruvius uses it of the vertical line or plane.^[2][5]
• c. 310–394 AD – Ausonius uses it figuratively of strict order.^[7][5]
• Medieval Latin – It also names a mason's rule and a pothook.^[8]

Meanings

Noun

1. A plumb line, plummet.^[2][6]
2. A vertical line or plane, a perpendicular.^[2]
3. ad perpendiculum: vertically, perpendicularly.^[2][6]
4. (Medieval Latin) A mason's rule, carpenter's square.^[8]
5. (Medieval Latin) A pothook.^[8]

Related words

• pendeō
• pondus

References

1. ^ a b c d Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f g h i j k l m Glare, P. G. W., ed. (2012), Oxford Latin Dictionary, 2nd ed., Oxford: Oxford University Press
3. ^ a b c Thesaurus linguae Latinae (1900–), Leipzig: Teubner; Berlin: De Gruyter; open-access ed., Munich: Bayerische Akademie der Wissenschaften
4. ^ a b c de Vaan, Michiel (2008), Etymological Dictionary of Latin and the other Italic Languages, Leiden Indo-European Etymological Dictionary Series 7, Leiden; Boston: Brill
5. ^ a b c d e Köbler, Gerhard (2010), Lateinisches Abkunfts- und Wirkungswörterbuch für Altertum und Mittelalter, online ed., koeblergerhard.de
6. ^ a b c d Lewis, Charlton T.; Short, Charles (1879), A Latin Dictionary, Oxford: Clarendon Press
7. ^ a b Georges, Karl Ernst (1913–1918), Ausführliches lateinisch-deutsches Handwörterbuch, 8th ed., ed. Heinrich Georges, Hannover; Leipzig: Hahn
8. ^ a b c d 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