Source : Webster's Revised Unabridged Dictionary (1913)

Sphenodon \Sphe"no*don\, n. [Gr. sfh`n a wedge + ???, ???, a
   tooth.] (Zo["o]l.)
   Same as {Hatteria}.

Hatteria \Hat*te"ri*a\, n. [NL.] (Zo["o]l.)
   A New Zealand lizard, which, in anatomical character, differs
   widely from all other existing lizards. It is the only living
   representative of the order Rhynchocephala, of which many
   Mesozoic fossil species are known; -- called also
   {Sphenodon}, and {Tuatera}.

Source : WordNet®

Sphenodon
     n : coextensive with the order Rhynchocephalia: tuataras [syn: {genus
         Sphenodon}]