Source : Webster's Revised Unabridged Dictionary (1913)

Epineurium \Ep`i*neu"ri*um\, n. [NL., fr. Gr. 'epi` upon + ? a
   nerve.] (Anat.)
   The connective tissue framework and sheath of a nerve which
   bind together the nerve bundles, each of which has its own
   special sheath, or perineurium.