Ephemera

Chamber's Etymological of the English Language · 1895 · p. 168

ef-em'er-a, n. a fly that lives one day only; the Mayfly, a genus of short-lived insects a fever of one day’s continuance only, [Gr. ephitneros living a day epi, for, and himera a day.J m mflte mOOn thsn. 168 Ephemeral