Evanescent \Ev`a*nes"cent\, a. [L. evanescens, -entis, p. pr. of evanescere.] 1. Liable to vanish or pass away like vapor; vanishing; fleeting; as, evanescent joys. So evanescent are the fashions of the world in these particulars. --Hawthorne. 2. Vanishing from notice; imperceptible. The difference between right and wrong, is some petty cases, is almost evanescent. --Wollaston. web1913

evanescent adj : tending to vanish like vapor; "evanescent beauty" wn