\Pe"dal\, a. [L. pedalis, fr. pes, pedis, foot. See
{Foot}, and cf. {Pew}.]
1. Of or pertaining to the foot, or to feet, literally or
   figuratively; specifically (Zo["o]l.), pertaining to the
   foot of a mollusk; as, the pedal ganglion.
2. Of or pertaining to a pedal; having pedals.
{Pedal curve} or {surface} (Geom.), the curve or surface
   which is the locus of the feet of perpendiculars let fall
   from a fixed point upon the straight lines tangent to a
   given curve, or upon the planes tangent to a given
   surface.
{Pedal note} (Mus.), the note which is held or sustained
   through an organ point. See {Organ point}, under {Organ}.
{Pedal organ} (Mus.), an organ which has pedals or a range of
   keys moved by the feet; that portion of a full organ which
   is played with the feet.

\Pe"dal\, n. [Cf. F. p['e]dale, 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.