EPHEMERAL
ephemeral, passing, short-lived, transient, transitory, fugacious
(adjective) lasting a very short time; “the ephemeral joys of childhood”; “a passing fancy”; “youth’s transient beauty”; “love is transitory but it is eternal”; “fugacious blossoms”
ephemeron, ephemeral
(noun) anything short-lived, as an insect that lives only for a day in its winged form
Source: WordNet® 3.1
Etymology
Noun
ephemeral (plural ephemerals)
Something which lasts for a short period of time.
Synonym: ephemeron
Adjective
ephemeral (comparative more ephemeral, superlative most ephemeral)
Lasting for a short period of time.
Synonyms: temporary, transitory, fleeting, evanescent, momentary, short-lived, short, volatile, Thesaurus:ephemeral
Antonyms: permanent, eternal, everlasting, timeless
(biology) Existing for only one day, as with some flowers, insects, and diseases.
(geology, of a body of water) Usually dry, but filling with water for brief periods during and after precipitation.
Source: Wiktionary
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 (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.
E*phem"er*al, n.
Definition: Anything lasting but a day, or a brief time; an ephemeral
plant, insect, etc.
Source: Webster’s Unabridged Dictionary 1913 Edition