Source : Webster's Revised Unabridged Dictionary (1913)

Amphisbaena \Am`phis*b[ae]"na\, n. [L., fr. Gr. ?; ? on both
   ends + ? to go.]
   1. A fabled serpent with a head at each end, moving either
      way. --Milton.

   2. (Zo["o]l.) A genus of harmless lizards, serpentlike in
      form, without legs, and with both ends so much alike that
      they appear to have a head at each, and ability to move
      either way. See Illustration in Appendix.

   Note: The {Gordius aquaticus}, or hairworm, has been called
         an {amphisb[ae]na}; but it belongs among the worms.

Source : WordNet®

amphisbaena
     n 1: (classical mythology) a serpent with a head at each end of
          its body
     2: type genus of the Amphisbaenidae [syn: {genus Amphisbaena},
        {Amphisbaenia}, {genus Amphisbaenia}]
     [also: {amphisbaenae} (pl)]