evanesce (v.)

"vanish by degrees, melt into thin air," 1817, a back-formation from evanescence, or else from Latin evanescere "disappear, vanish, pass away," figuratively "be forgotten, be wasted," from assimilated form of ex "out" (see ex-) + vanescere "vanish," inchoative verb from vanus "empty, void" (from PIE *wano-, suffixed form of root *eue- "to leave, abandon, give out").