perpendicular

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

Related words

• perpendicle
• pendulum
• pendant
• perpend
• pension

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