Definition of Ordovician in US English:



  • 1Relating to or denoting the second period of the Paleozoic era, between the Cambrian and Silurian periods.

    The Ordovician lasted from about 510 million to 439 million years ago. It saw the diversification of many invertebrate groups and the appearance of the first vertebrates (jawless fish)

    • ‘They interpreted these dates to represent an Ordovician regional metamorphic event.’
    • ‘In contrast, the Ordovician magmatic event postdates the pre-Variscan deformation in the external zone.’
    • ‘Additional indications for a potential tectonic boundary in Hinnoy are provided by local evidence of an Ordovician event in basement units of the Lofoten area.’
    • ‘Because of the disparate nature of the Ordovician and Cambrian records, it is difficult to make direct comparison between the two events.’
    • ‘These are overlain by low-grade metamorphosed sediments and volcanics of Ordovician and Silurian age.’
    1. 1.1as noun the Ordovician The Ordovician period or the system of rocks deposited during it.


Late 19th century: from Ordovices, the Latin name of an ancient British tribe in North Wales, + -ian.