pendulum

Borrowed from the neuter of Latin pendulus (“hanging”).

• IPA^(key): /ˈpɛnd͡ʒələm/
• US (some regions): IPA^(key): /ˈpɪnd͡ʒələm/

• Audio (US)

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pendulum (plural pendulums or pendula) (See usage notes.)

1. (clocks, mechanics) A body suspended from a fixed support so that it swings freely back and forth under the influence of gravity, commonly used to regulate various devices such as clocks.
   1. (by extension) Used to refer to the tendency of a situation to oscillate (between two extremes).
      • 2021 October 20, Industry Insider, “The wheels turn slowly”, in RAIL, number 942, page 68:

        The pendulum can be seen to be swinging in favour of rail, as with each issue of RAIL comes news of further intermodal service expansion.

2. A lamp, etc. suspended from a ceiling.
3. A watch's guard-ring by which it is attached to a chain.

The plural form pendula is significantly rarer than pendulums; see etymology at pendula for details. However, pendula is occasionally used in physics.

• Foucault’s pendulum
• pendant

• simple harmonic motion

• “pendulum”, in Lexico, Dictionary.com; Oxford University Press, 2019–2022.

• unplumed

pendulum

1. inflection of pendulus:
   1. nominative/accusative/vocative neuter singular
   2. accusative masculine singular

• pendulum in Charles du Fresne du Cange’s Glossarium Mediæ et Infimæ Latinitatis (augmented edition with additions by D. P. Carpenterius, Adelungius and others, edited by Léopold Favre, 1883–1887)