Source : Webster's Revised Unabridged Dictionary (1913)

Mesozoic \Mes`o*zo"ic\, a. [Meso- + Gr. ? life, fr. ? to live.]
   (Geol.)
   Belonging, or relating, to the secondary or reptilian age, or
   the era between the Paleozoic and Cenozoic. See Chart of
   {Geology}.

Mesozoic \Mes`o*zo"ic\, n.
   The Mesozoic age or formation.

Source : WordNet®

Mesozoic
     n : from 230 million to 63 million years ago [syn: {Mesozoic era},
          {Age of Reptiles}]