SILURIAN
Silurian, Silurian period
(noun) from 425 million to 405 million years ago; first air-breathing animals
Source: WordNet® 3.1
Adjective
Silurian (comparative more Silurian, superlative most Silurian)
(geology) Of a geologic period within the Paleozoic era; comprises the Llandovery, Wenlock, Ludlow and Pridoli epochs from about 439 to 409 million years ago.
(archaeology) Of or related to the Silures, a pre-Roman British tribe.
Proper noun
Silurian
(geology) The Silurian period.
Source: Wiktionary
Si*lu"ri*an, a. Etym: [From L. Silures, a people who anciently
inhabited a part of England and Wales.] (Geol.)
Definition: Of or pertaining to the country of the ancient Silures; -- a
term applied to the earliest of the Paleozoic eras, and also to the
strata of the era, because most plainly developed in that country.
Note: The Silurian formation, so named by Murchison, is divided into
the Upper Silurian and Lower Silurian. The lower part of the Lower
Silurian, with some underlying beds, is now separated under the name
Cambrian, first given by Sedwick. Recently the term Ordovician has
been proposed for the Lower Silurian, leawing the original word to
apply only to the Upper Silurian.
Si*lu"ri*an, n.
Definition: The Silurian age.
Source: Webster’s Unabridged Dictionary 1913 Edition