pendulum

Etymology

It is borrowed from New Latin pendulum (“a free-hanging body”),^[2][3][4][5] recorded in 1643 in the title of a work,^[2][3] the neuter of Latin pendulus (“hanging down”) used as a noun,^{[2][3][6][7][8]} from pendeō (“to hang”),^[3][4][6][9] which Etymonline traces to Proto-Indo-European *(s)pen- (“to draw, stretch, spin”).^[3] The Latin adjective is also the source of pendulous.^[6][5] The American Heritage Dictionary takes the New Latin word as probably from Italian pendolo (“pendulous; pendulum”),^[10] and Barnhart and Etymonline as perhaps a Latinized form of it;^[4][3] the OED records the Italian noun from before 1631, in Galileo, and earlier, from 1282, in the sense "dangling cluster",^[2] while Barnhart dates Galileo's use to 1637.^[4] Klein says that Robert Boyle introduced the word into English.^[11] The OED compares perpendiculum (“plumb line”).^[2]

Earliest recorded meaning

A weight on a rod or cord, hung from a fixed point so that it swings freely under gravity: 1660, in Robert Boyle's New Experiments Physico-Mechanical.^[2][4][3]

Semantic evolution

The OED notes that Galileo was the first to study the properties of the pendulum, around 1583.^[2] The device was soon used to regulate clocks; from 1664 to 1707 pendulum could mean a pendulum clock or watch itself;^[2] Weekley quotes Evelyn (1661) on Huygens as the inventor of the pendule clock, and notes that pendule, pendolo and Pendel all date from the 17th century.^[9] Johnson (1755) defined it as any weight hung so that it can swing back and forth, its swings always taking equal time.^[12] The figurative sense, a person or thing that swings between opposite positions, as public opinion or fashion, is recorded from 1765,^[2] and the Letters of Junius asked in 1769 whether a minister's conduct was wisdom or the vibration of a pendulum.^[9] The noun was used of the penis in slang, recorded by Farmer and Henley around 1890–1904.^[13] In mountaineering, from 1945, a pendulum is a swing on a rope to reach a new position,^[2] and the verb to pendulum, to swing like a pendulum, chiefly in climbing, is recorded from 1885.^[2][14]

Timeline

• 1660 – a weight hung from a fixed point so as to swing freely.^[2][4][7]
• 1664 – a pendulum clock or watch (obsolete by 1707).^[2]
• 1765 – figurative, something that swings between opposite positions.^[2]
• 1773 – an inverted pendulum, fixed at its base.^[2]
• 1885 – verb, to swing like a pendulum.^[2]
• 1945 – mountaineering, a swing on a rope to a new position.^[2]

Meanings

Noun

1. A body hung from a fixed point so that it swings freely back and forth under gravity, especially one used to regulate a clock: The grandfather clock stopped when its pendulum caught on the case.^{[10][15][7][2]}
2. Something that swings between opposite opinions, courses or conditions: the pendulum of public opinion.^[10][15][7]
3. (mountaineering) A swing on a rope used by a climber to reach a new position.^[2]

Verb

1. To swing like a pendulum, especially (in climbing) on a rope to reach another part of a rock face.^[2][14]

Word family

• pendulumlike
• ballistic pendulum
• compound pendulum
• Foucault pendulum
• torsion pendulum
• simple pendulum

Related words

• pendant
• pendulous
• pendent
• pending
• penchant
• depend
• suspend
• append
• perpendicular

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 Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
3. ^ a b c d e f g Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
4. ^ a b c d e f Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
5. ^ a b Hoad, T. F., ed. (1986), The Concise Oxford Dictionary of English Etymology, Oxford: Clarendon Press
6. ^ a b c Ayto, John (2005), Word Origins: The Secret Histories of English Words from A to Z, 2nd ed., London: A & C Black
7. ^ a b c d Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
8. ^ Stevenson, Angus, ed. (2010), Oxford Dictionary of English, 3rd ed., Oxford: Oxford University Press
9. ^ a b c Weekley, Ernest (1921), An Etymological Dictionary of Modern English, London: John Murray
10. ^ a b c The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
11. ^ Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
12. ^ Johnson, Samuel (1755), A Dictionary of the English Language, London; 4th ed. 1773; Johnson's Dictionary Online, ed. Beth Rapp Young et al.
13. ^ Green, Jonathon (2010), Green's Dictionary of Slang, London: Chambers; digital ed. 2016–, https://greensdictofslang.com
14. ^ a b Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
15. ^ a b Collins English Dictionary (2023), Glasgow: HarperCollins