a bright light that shines for a short time and then stops shining:
Two flashes mean danger.
a brilliant flash of light
a special bright light used when taking photographs indoors or when there is not much light:
camera[uncountable and countable]TCP
Did the flash go off?
3 also quick as a flash
Just wait here. I'll be back in a flash.
if someone has a flash of brilliance, anger etc, they suddenly have a clever idea or a particular feeling
a sudden success that ends quickly and is unlikely to happen again:
Beene's new novel proves he isn't just a flash in the pan.
if there is a flash of something brightly coloured or shiny, it appears suddenly for a short time
bright colour/something shiny[countable]
The bird vanished in a flash of blue.
a system of instructions for a computer that is used especially to make pictures on a website appear to move:
a quick look used humorously [= glimpse]
look[countable] British English
a small piece of coloured cloth worn on the shoulder of a military uniform