Ordovician

2 definitions found

From The Collaborative International Dictionary of English v.0.48 [gcide]:

  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]

From WordNet (r) 2.0 [wn]:

  Ordovician
       n : from 500 million to 425 million years ago; conodonts and
           ostracods and algae and seaweeds [syn: {Ordovician period}]