We don't have synonyms for ordovian yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are cordovan, ordovician and rovian.
(adj) :
Alternative form of Ordovician. [(geology) Of a geologic period within the Paleozoic era; comprises lower, middle and upper epochs from about 488 to 443 million years ago.]
(n) :
Alternative form of Ordovician. [(geology) The Ordovician period.]
(adj) :
Alternative form of Ordovician. [(geology) Of a geologic period within the Paleozoic era; comprises lower, middle and upper epochs from about 488 to 443 million years ago.]
(n) :
Alternative form of Ordovician. [(geology) The Ordovician period.]