Found 2 items, similar to Ordovician.
English → English (WordNet) Definition: Ordovician Ordovician n : from 500 million to 425 million years ago; conodonts and ostracods and algae and seaweeds [syn: Ordovician period]
English → English (gcide) Definition: Ordovician Ordovician \Or`do*vi"cian\, a. [From L. Ordovices, a Celtic people in Wales.] (Geol.) Of or pertaining to a division of the Silurian formation, corresponding in general to the Lower Silurian of most authors, exclusive of the Cambrian. -- n. The Ordovician formation. [1913 Webster]