dinosaurnoun/ˈdaɪnəsɔː(ɹ)/

• 1

  Those animals of the clade Dinosauria that existed during the Triassic, Jurassic and Cretaceous periods and are now extinct.

  • Despite what some cartoons portray, no humans were around when dinosaurs roamed the Earth.
• 2

  Any of the animals belonging to the clade Dinosauria, including its sole surviving lineage: Neornithes.

  • Many people love their backyard birds, but some of us may not realize that those feathery friends are also literally dinosaurs, in a biologically accurate sense of that word.
• 3

  informalAny extinct reptile, not necessarily belonging to Dinosauria, that existed between about 230 million and 65 million years ago, as well as the stem-mammal Dimetrodon.

  • Pterosaurs, plesiosaurs, icthyosaurs — I don't know, they're all dinosaurs to me!
  • "Not a bird, my dear Roxton - not a bird." "A beast?" "No; a reptile - a dinosaur."
• 4

  Someone or something that is very old or old-fashioned, especially someone who is not willing to change and adapt.

  • She may be a tough old bird, but it's a mistake to write her off as a dinosaur; you do so at your own risk.
  • [The OS/360 linkage editor] is the culmination of years of development of static overlay technique. Yet it is also the last and finest of the dinosaurs, for it belongs to a system in which multiprogramming is the normal mode and dynamic core allocation the basic assumption.
• 5

  Anything no longer in common use or practice.

  • I couldn't believe it when I saw the equipment that they were still using. Those machines were all dinosaurs, but they were busily cranking out production.