A word a day.

ephemeral \ih-FEM-er-ul\, adjective:
1. Beginning and ending in a day; existing only, or no longer than, a day; as, an ephemeral flower.
2. Short-lived; existing or continuing for a short time only.

Success is very ephemeral. You depend entirely on the desire of others, which makes it difficult to relax.-- Eva Green

In "Mississippi Mermaid," the planter character played by Belmondo, a fellow who has sought a safe, permanent love, is liberated when he chooses to follow the ephemeral.-- Vincent Canby, "Truffaut's Clear-Eyed Quest.", New York Times, September 14, 1975

Rather, we must separate what is ephemeral... from the things that are of lasting importance.-- Patrick Smith, Japan: A Reinterpretation