silurian period Silurian • Siluric · · · Info · Definitions · Characters · · silurian period · · Text Common · · Latin · · Scripts 15 · · Length 6 · · Syllables Definitions · · · (noun) from 425 million to 405 million years ago; first air-breathing animals. Synonyms: Silurian, Silurian period. · · Noun Definition 1 Characters · · space U+0020 a latin small letter a U+0061 d latin small letter d U+0064 e latin small letter e U+0065 i latin small letter i U+0069 l latin small letter l U+006C n latin small letter n U+006E o latin small letter o U+006F p latin small letter p U+0070 r latin small letter r U+0072 s latin small letter s U+0073 u latin small letter u U+0075