Jurassic

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective Of, relating to, or being the period of geologic time from about 199 to 145 million years ago, the second period of the Mesozoic Era, in which dinosaurs were the dominant form of terrestrial animal life, and the earliest birds appeared.
• noun The Jurassic Period.

from The Century Dictionary.

• Pertaining or relating to the Jura mountains, and specifically, in geology, to the Jurassic series.
• noun In geology, that part of the geological series which includes all the groups and subgroups older than the Cretaceous and newer than the Triassic: so called from the predominance of rocks of this age in the Jura mountains.

from the GNU version of the Collaborative International Dictionary of English.

• adjective (Geol.) Of the age of the middle Mesozoic, about 190 to 140 million years ago, including, as divided in England and Europe, the Lias, Oölite, and Wealden; -- named from certain rocks of the Jura mountains. It was noted for the predominance of dinosaurs on land, and the development of the first birds and mammals.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective geology Of or pertaining to the second period of the Mesozoic era, a time still dominated by dinosaurs.
• adjective Of or pertaining to the people or region near the Jura Mountain Range of Europe.
• proper noun The period from 200 to 146 million years ago, after the Triassic and before the Cretaceous; the geologic formations of this period.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• adjective of or relating to or denoting the second period of the Mesozoic era
• noun from 190 million to 135 million years ago; dinosaurs; conifers