ephemeral

(noun) anything short-lived, as an insect that lives only for a day in its winged form. Synonyms: ephemeron.

(adj) lasting a very short time. Synonyms: passing, short-lived, transient, transitory, fugacious. Examples: "The ephemeral joys of childhood." "A passing fancy." "Youth's transient beauty." "Love is transitory but it is eternal." "Fugacious blossoms."