Pendulum
WordNet
noun
(1) An apparatus consisting of an object mounted so that it swings freely under the influence of gravity
WiktionaryText
Noun
- 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.
Usage notes
The plural form is hypercorrect, and significantly rarer than ; see etymology at for details. However, pendula is widely used in physics.
Adjective
pendulum