Pe″dal (pĕd″al), n. [Cf. F. pédale, It. pedale. See Pedal, a.] 1. (Mech.) A lever or key acted on by the foot, as in the pianoforte to raise the dampers, or in the organ to open and close certain pipes; a treadle, as in a lathe or a bicycle.
2. (Geom.) A pedal curve or surface.