- noun a weight on the end of a chain which swings from side to side, making a clock work
- noun a trend from one extreme to another
- A rigid body which freely swings about a fixed point. A simple pendulum may be considered to have a point mass whose path is symmetrical about a given equilibrium position, and whose movement is influenced only by gravity. Used, for instance, to demonstrate simple harmonic motion, or to determine the value of the gravitational acceleration of the planet earth.