pendulum

pendulum n

L., free-hanging body.

1. Time-keeping device; rhythmically oscillating body which serves to mark the passage of time.
2. Metronome; [fig.] cricket; rhythmically chirping insect; creature whose appearance and disappearance marks the passage of the seasons.
3. [Fig.] heart; life-regulating apparatus of the human body; rhythmically contracting muscular organ.
4. [Fig.] usual order of things; commonly perceived laws of reality.