Source : Webster's Revised Unabridged Dictionary (1913)

Jurassic \Ju*ras"sic\, a. (Geol.)
   Of the age of the middle Mesozoic, including, as divided in
   England and Europe, the Lias, O["o]lite, and Wealden; --
   named from certain rocks of the Jura mountains. -- n. The
   Jurassic period or formation; -- called also the {Jura}.

Source : WordNet®

Jurassic
     n : from 190 million to 135 million years ago; dinosaurs;
         conifers [syn: {Jurassic period}]