Flashing definition

From original flashing material of copper or aluminum that reflects flashes of sunlight.

Components used to weatherproof or seal roof system edges at perimeters, penetrations, walls, expansion joints, valleys, drains and other places where the roof covering is interrupted or terminated.
The process of getting rid of gaps on shelves by bringing products from the back of the shelf to the front to create a 'fuller' shelf.
The blinking of a light source, such as a light bulb or computer's cursor.

The incessant flashing of the neon sign kept the neighborhood awake.
An incidence of indecent exposure.