1. n. (pl. ephemeras or ephemerae)
1. a an insect living only a day or a few days. b any insect of the order Ephemeroptera, e.g. the mayfly.
2 EPHEMERON.
Etymology: mod.L f. Gk ephemeros lasting only a day (as EPI-, hemera day) 2. pl. of EPHEMERON 1.