Definitions for ordovicianˌɔr dəˈvɪʃ ən
Random House Webster's College Dictionary
Or•do•vi•cianˌɔr dəˈvɪʃ ən(adj.)
noting or pertaining to a geologic period of the Paleozoic Era, from 500 million to 425 million years ago, notable for the advent of fish.
(n.)the Ordovician Period or System.
Origin of Ordovician:
1879; after the Ordovices (pl.) (< L) an ancient British tribe in N Wales
Ordovician, Ordovician period(noun)
from 500 million to 425 million years ago; conodonts and ostracods and algae and seaweeds
Of a geologic period within the Paleozoic era; comprises lower, middle and upper epochs from about 488 to 443 million years ago.
The Ordovician period.