Use 'evanescent' to describe something that fades out or ends rapidly, not just physically but perhaps in memory or importance. The evanescent flash of a shooting star captivated me.
Pro Tip 2/3
Seldom Negative
'Evanescent' often has a neutral or slightly positive connotation, not usually used in a negative context. The evanescent glow of city lights at night was enchanting.
Pro Tip 3/3
Poetic Expression
'Evanescent' is popular in literary or poetic contexts for its descriptive elegance. Her laughter was evanescent, lingering briefly in the air before fading.