Evanescent
Evanescent , adjective
[Latin evanescens, -entis, present participle 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.
2.
Vanishing from notice; imperceptible.
The difference between right and wrong, in some petty cases, is almost evanescent.