Source : Webster's Revised Unabridged Dictionary (1913)

Dinosaur \Di"no*saur\, Dinosaurian \Di`no*sau"ri*an\, n. [Gr. ?
   terrible + ? lizard.] (Paleon.)
   One of the Dinosauria. [Written also {deinosaur}, and
   {deinosaurian}.]

Source : WordNet®

dinosaur
     n : any of numerous extinct terrestrial reptiles of the Mesozoic
         era

Source : Free On-Line Dictionary of Computing

dinosaur
     
        1. Any hardware requiring raised flooring and special power.
        Used especially of old {minicomputer}s and {mainframe}s, in
        contrast with newer {microprocessor}-based machines.
     
        In a famous quote from the 1988 Unix EXPO, {Bill Joy} compared
        the liquid-cooled mainframe in the massive {IBM} display with
        a grazing dinosaur "with a truck outside pumping its bodily
        fluids through it".  IBM was not amused.
     
        Compare {big iron}; see also {dinosaurs mating}.
     
        2. [IBM] A very conservative user; a {zipperhead}.
     
        [{Jargon File}]