A Pedal

1. A lever operated by one's foot that is used to control or power a machine or mechanism, such as a bicycle or piano
2. (medicine) an orthopedic structure or a footlike part.
3. (music) An effects unit, especially one designed to be activated by being stepped on.
4. (equestrianism, humorous) A stirrup.
5. (music) The ranks of pipes played from the pedal-board of an organ