A weight hung from a fixed point so that it can swing freely backward and forward, especially a rod with a weight at the end that regulates the mechanism of a clock.

The pendulum in the grandfather clock swung back and forth, marking the passage of time.

A metaphor for something that alternates between two extremes or opposites.

The political pendulum has swung from conservative to liberal policies over the decades.

pendulumadjective

Relating to or characteristic of a pendulum, especially functioning by means of a swinging weight.

The watch features a pendulum movement for increased accuracy.