ordovician period is a noun meaning "from 500 million to 425 million years ago; conodonts and ostracods and algae and seaweeds". It carries one recorded sense.
from 500 million to 425 million years ago; conodonts and ostracods and algae and seaweeds
Definitions, synonyms and semantic relations for ordovician period come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.