Source : Webster's Revised Unabridged Dictionary (1913)

Lemniscus \Lem*nis"cus\ (l[e^]m*n[i^]s"k[u^]s), n.; pl.
   {Lemnisci} (-s[imac]). [L. See {Lemniscata}.] (Zo["o]l.)
   One of two oval bodies hanging from the interior walls of the
   body in the Acanthocephala.

Source : WordNet®

lemniscus
     n : a bundle of sensory nerve fibers going to the thalamus [syn:
          {fillet}]
     [also: {lemnisci} (pl)]