Source : Webster's Revised Unabridged Dictionary (1913)

Plantar \Plan"tar\, a. [L. plantaris, fr. planta the sole of the
   foot.] (Anat.)
   Of or pertaining to the sole of the foot; as, the plantar
   arteries.

Source : WordNet®

plantar
     adj : relating to or occurring on the undersurface of the foot;
           "plantar warts can be very painful"