Eocene Eocarboniferous • Eodevonian · · · Info · Definitions · Characters · · Eocene · · Text Latin · · Script 6 · · Length Definitions · · · (noun) from 58 million to 40 million years ago; presence of modern mammals. Synonyms: Eocene epoch. · · Noun Definition 1 Characters · · E latin capital letter e U+0045 c latin small letter c U+0063 e latin small letter e U+0065 n latin small letter n U+006E o latin small letter o U+006F