\E*phem"e*ra\, n. [NL., fr. Gr. ? a day fly, fr. ?
daily, lasting but a day; ? over + ? day.]
1. (Med.) A fever of one day's continuance only.
2. (Zo["o]l.) A genus of insects including the day flies, or
   ephemeral flies. See {Ephemeral fly}, under {Ephemeral}.