Ephemeral (?), a. 1. Beginning and ending in a day; existing only, or no longer than, a day; diurnal; as, an ephemeral flower.
[1913 Webster]

2. Short-lived; existing or continuing for a short time only. “Ephemeral popularity.” V. Knox.
[1913 Webster]

Sentences not of ephemeral, but of eternal, efficacy. Sir J. Stephen.
[1913 Webster]

Ephemeral fly (Zoöl.), one of a group of neuropterous insects, belonging to the genus Ephemera and many allied genera, which live in the adult or winged state only for a short time. The larvæ are aquatic; -- called also day fly and May fly.
[1913 Webster]