pedal

Short definition from Wiktionary

Noun

1. 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. 2
   an orthopedic structure or a footlike part.
3. 3
   An effects unit, especially one designed to be activated by being stepped on.
4. 4
   A stirrup.
5. 5
   The ranks of pipes played from the pedal-board of an organ.

Verb

1. 1
   To operate a pedal attached to a wheel in a continuous circular motion.
2. 2
   To operate a bicycle.

Adjective

1. 1
   Of or relating to the foot.