Source : Webster's Revised Unabridged Dictionary (1913)

Interbrain \In`ter*brain`\, n. (Anat.)
   See {Thalamencephalon}.

Source : WordNet®

interbrain
     n : the posterior division of the forebrain; connects the
         cerebral hemispheres with the mesencephalon [syn: {diencephalon},
          {betweenbrain}, {thalmencephalon}]