1. 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, especially clocks. Also called simple pendulum.
2. Something that swings back and forth from one course, opinion, or condition to another: the pendulum of public opinion.

[New Latin, probably from Italian pendolo, pendulous, pendulum, from Latin pendulus, hanging. See pendulous.]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.