pendulum
noun(pen-du-lum)
a body suspended from a fixed point so as to swing freely to and fro under the action of gravity and commonly used to regulate movements (as of clockwork)
pendulum
noun(pen-du-lum)
something (such as a state of affairs) that alternates between opposites
pendulum
noun(pen-du-lum)
a freely swinging pendulum that consists of a heavy weight hung by a long wire and that swings in a constant direction which appears to change showing that the earth rotates