Ephemeroptera ephemeron • ephemerous · · · Info · Definitions · Characters · · Ephemeroptera · · Text Latin · · Script 13 · · Length Definitions · · · (noun) mayflies. Synonyms: order Ephemeroptera, Ephemerida, order Ephemerida. · · Noun Definition 1 Characters · · E latin capital letter e U+0045 a latin small letter a U+0061 e latin small letter e U+0065 h latin small letter h U+0068 m latin small letter m U+006D o latin small letter o U+006F p latin small letter p U+0070 r latin small letter r U+0072 t latin small letter t U+0074