Source : Webster's Revised Unabridged Dictionary (1913)

Metatarsus \Met`a*tar"sus\, n.; pl. {Metatarsi}. [NL. See
   {Meta-}, and {Tarsus}.] (Anat.)
   That part of the skeleton of the hind or lower limb between
   the tarsus and phalanges; metatarse. It consists, in the
   human foot, of five bones. See Illustration in Appendix.

Source : WordNet®

metatarsus
     n : the skeleton of the human foot between the toes and the
         tarsus; the corresponding part of the foot in birds or of
         the hind foot in quadrupeds
     [also: {metatarsi} (pl)]

metatarsi
     See {metatarsus}