A visual illusion wherein a flash and a moving object that appear in the same location are perceived to be displaced from one another.

plural of flash-lag illusion

plural of flash-lag effect

Used ironically to introduce a sobering truth.

A lamp that produces a very short, but very intense, flash of white light; used in photography and in photocoagulation

(roofing) Flashing, usually composed of metal, used to cover or shield the upper edges of the membrane base flashing; wall flashing can also be used to cover the top of various building components, such as parapets or columns.

plural of blue flash

(roofing) Plies or strips of roof membrane material used to close-off and/or seal a roof at the horizonta-to-vertical intersections. Membrane base flashing covers the edge of the field membrane.

(roofing) an accessory flashing used to cover and/or seal soil pipe vents and other penetrations through a roof (sometimes referred to as roof jack or flashing boot).

(roofing) Individual pieces of sheet metal material used to flash walls, around chimneys, dormers and such projections along the slope of a roof. Individual pieces are overlapped and stepped up the vertical wall.