Webster’s Revised Unabridged Dictionary · 1913
Evanescent
Ev′a·nes′cent (·sent), 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.