from The American Heritage® Dictionary of the English Language, 4th Edition

  • adj. Of or belonging to the geologic time, system of rocks, or sedimentary deposits of the first period of the Mesozoic Era, characterized by the diversification of land life, the rise of dinosaurs, and the appearance of the earliest mammals. See Table at geologic time.
  • n. The Triassic Period or its system of deposits.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • adj. Of or from the geologic strata above the Permian and below the Jurassic; of or belonging to the period 250 to 200 million years ago when these strata were laid down.
  • proper n. A geologic period within the Mesozoic era; comprises lower, middle and upper epochs from about 250 to 200 million years ago.

from the GNU version of the Collaborative International Dictionary of English

  • adj. Of the age of, or pertaining to, the Trias.

from The Century Dictionary and Cyclopedia

  • n. In geology, the lower of the three great divisions of the entire system of fossiliferous rocks (Triassic, Jurassic, Cretaceous) which together make up the Mesozoic or Secondary series.

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

  • adj. of or relating to or denoting the first period of the Mesozoic era
  • n. from 230 million to 190 million years ago; dinosaurs, marine reptiles; volcanic activity


Late Latin trias, triad (from the subdivision of this period into three parts); see triad + -ic.
(American Heritage® Dictionary of the English Language, Fourth Edition)
1841, coined by geologist Friedrich August von Alberti (1795–1878). From Trias ("three-layered geologic strata between the Permian and Jurassic") < German Trias < Ancient Greek τριάς (triás, "triad") + -ic. (Wiktionary)



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