:

lasting a very short   time

The young pop star’s   fame turned out to be ephemeral.

“During the   creation of the ephemeral show—the walls will be erased for a new   exhibition later this month, leaving only a series of framed drawings   behind—Ms. Dary visited the local library and copied pages from a   100-year-old local directory.” — From an article by Tammy La Gorce in   the New York Times, January 4, 2013

The mayfly (order   Ephemeroptera) typically hatches, matures, mates, and dies within the span of   a few short hours (though the longest-lived species may survive a record two   days); poets sometimes use this insect to symbolize life’s ephemeral nature.   When “ephemeral” (from the Greek word “ephēmeros,”   meaning “lasting a day”) first appeared in print in English in the   late 16th century, it was a scientific term applied to short-term fevers, and   later, to organisms (such as insects and flowers) with very short life spans.   Soon after that, it acquired an extended sense referring to anything fleeting   and short-lived (as in “ephemeral pleasures”).