evanescent

Borrowed from French évanescent (“evanescent”), from Latin ēvānēscēns (“disappearing, vanishing”), present participle of ēvānēscō (“to disappear, vanish; to die out, fade away; to lapse”), from ē- (variant of ex- (prefix meaning ‘away, out’)) + vānēscō (“to vanish”) (from vānus (“empty, vacant, void”), from Proto-Indo-European *h₁weh₂- (“to abandon, leave”)) + -ēscō (suffix forming verbs with the sense ‘to become’)).