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 second period of the Paleozoic Era, characterized by the appearance of primitive fishes. See Table at geologic time.
- n. The Ordovician Period.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- adj. Of a geologic period within the Paleozoic era; comprises lower, middle and upper epochs from about 488 to 443 million years ago.
- proper n. The Ordovician period.
from the GNU version of the Collaborative International Dictionary of English
- adj. Of or pertaining to a division of the Silurian formation, corresponding in general to the Lower Silurian of most authors, exclusive of the Cambrian.
from The Century Dictionary and Cyclopedia
- An epithet applied by C. Lapworth to a series of rocks not capable of exact separation from those underlying or overlying them, either stratigraphically or paleontologically, but which have been the subject of much discussion among English geologists.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. from 500 million to 425 million years ago; conodonts and ostracods and algae and seaweeds
From Latin Ordovicēs, an ancient Celtic tribe of Wales, from Celtic Ordovices.(American Heritage® Dictionary of the English Language, Fourth Edition)