Today is National One-Hit Wonder Day, a day to celebrate acts who have had the bittersweet joy of having one and only one musical hit scale the charts. The literary field has its own assortment of one-hit wonders — think of Harper Lee and To Kill a Mockingbird or John Kennedy O'Toole and A Confederacy of Dunces.

Of course, such ephemerality is not restricted to music and literature. Entomologists know the genus name of the short-lived mayfly as ephemera, and gardeners are familiar with plant varieties (such as flower-of-an-hour and fameflower) called ephemerals, specimens noted for growing, flowering, and dying in only a few short days.

So where does the word ephemeral come from? Its Greek ancestor literally meant "lasting a day"; in addition to its adjectival senses meaning "lasting one day only" and "lasting a very short time," our English word turns up as part of ephemeral stream (a stream that flows only briefly during and following a period of rainfall in the immediate locality) and ephemeral fever, a three-day fever of cattle.

One sense of ephemeral—actually, of ephemera— is itself a relative newcomer, dating back only to the middle of the last century. That's when collectors began using the plural ephemera to refer to collectibles such as posters, broadsides, and tickets not intended to have lasting value.