'Pedal surface' definitions:

Definition of 'Pedal surface'

From: GCIDE

Pedal \Pe"dal\ (p[=e]"dal in def 1; 277), 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 (Zool.), pertaining to the foot of a mollusk; as, the pedal ganglion. [1913 Webster]
2. (p[e^]d"al) Of or pertaining to a pedal; having pedals. [1913 Webster]
Pedal curve or Pedal 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. [1913 Webster]