What does "pedal" mean?

Pedal: ( 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.