Definition from Wiktionary, the free dictionary
flashing (plural flashings)
- (roofing) 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.
- The exposing of one's naked body, or part of it, in public briefly (the action of the verb to flash).
exposing one's naked body, or part of it
Derived terms 
- apron flashing
- base flashing
- cap flashing
- channel flashing
- flashing collar
- skirt flashing
- step flashing
- Present participle of flash.