fleet·ing

-adjective

1.passing swiftly; vanishing quickly; transient; transitory; fleeting beauty; a fleeting glance.

2. "A new architectural space is constructed within the accelerated flow of substitute images: 'Besides the enlargement of the physical world now available to our direct experience, these media virtually extend our physical environment, providing a constant stream of moving, fleeting images of the world for our daily appraisal...'"

References - Recycling Recycling, Mark Wigley; www.dictionary.reference.com