Source : Webster's Revised Unabridged Dictionary (1913)

Ephemeral \E*phem"er*al\, a.
   1. Beginning and ending in a day; existing only, or no longer
      than, a day; diurnal; as, an ephemeral flower.

   2. Short-lived; existing or continuing for a short time only.
      ``Ephemeral popularity.'' --V. Knox.

            Sentences not of ephemeral, but of eternal,
            efficacy.                             --Sir J.
                                                  Stephen.

   {Ephemeral fly} (Zo["o]l.), 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 larv[ae] are aquatic; -- called also {day
      fly} and {May fly}.

Ephemeral \E*phem"er*al\, n.
   Anything lasting but a day, or a brief time; an ephemeral
   plant, insect, etc.

Source : WordNet®

ephemeral
     adj : enduring a very short time; "the ephemeral joys of
           childhood"; "a passing fancy"; "youth's transient
           beauty"; "love is transitory but at is eternal";
           "fugacious blossoms" [syn: {passing}, {short-lived}, {transient},
            {transitory}, {fugacious}]