English definition of “flash”
BRIGHT LIGHT [C] › a sudden bright light: The bomb exploded in a flash of yellow light.
CAMERA [C, U] › a piece of camera equipment that produces a bright light when you take a photograph in a dark place
SUDDEN EXPERIENCE [C] › a sudden experience of something such as a feeling or idea: a flash of anger I had a flash of inspiration.
in a flash › immediately, or very quickly: I'll be back in a flash.