Source : Webster's Revised Unabridged Dictionary (1913)

Intermedium \In`ter*me"di*um\, n.; pl. {Intermediums}, L.
   {Intermedia}. [NL., neut. of L. intermedius intermediate.]
   1. Intermediate space. [R.]

   2. An intervening agent or instrument. --Cowper.

   3. (Anat.) The bone or cartilage between the radiale and
      ulnare in the carpus, and between the tibiale and fibulare
      in the tarsus. It corresponds to the lunar in the carpus,
      and to a part of the astragalus in the tarsus of man and
      most mammals.