evanescence

evanescence \ev-uh-NES-ens\, noun:

1. A gradual dissappearance.
2. The state of becoming imperceptible.

This is one of the most beautiful circumstances connected with water surface, for by these means a variety of color and a grace and evanescence are introduced in the reflection otherwise impossible.
-- John Ruskin, The Works of John Ruskin: Modern painters, v.1-5

But this was an evanescence, and quickly repented of, as it were, by an immitigable look, pinching and shriveling the visage into the momentary semblance of a wrinkled walnut.
-- Herman Melville, Billy Budd, sailor: (an inside narrative)

Evanescence is from Latin evanescere, "to vanish," from e-, "from, out of" + vanescere, "to disappear," from vanus, "empty."