Source : Webster's Revised Unabridged Dictionary (1913)

Metathorax \Met`a*tho"rax\, n. [NL.: cf. F. m['e]tathorax. See
   {Meta-}, and {Thorax}.] (Zo["o]l.)
   The last or posterior segment of the thorax in insects. See
   Illust. of {Coleoptera}.