To burst forth into or as if into flame. To give off light or be lighted in sudden or intermittent bursts. To appear or occur suddenly: The image flashed onto the screen. To move or proceed rapidly: The cars flashed by. To hang up a phone line momentarily, as when using call waiting. Slang To think of or remember something suddenly: flashed on that time we got caught in the storm. Slang To expose oneself in an indecent manner. To cause (light) to appear suddenly or in intermittent bursts. To cause to burst into flame. To reflect (light). To cause to reflect light from (a surface). To make known or signal by flashing lights. To communicate or display at great speed: flashed the news to the world capitals. To exhibit briefly. To hang up (a phone line) momentarily, as when using call waiting. To display ostentatiously; flaunt. To fill suddenly with water. To cover with a thin protective layer. A sudden, brief, intense display of light. A sudden perception: a flash of insight. A split second; an instant: I'll be on my way in a flash. A brief news dispatch or transmission. Slang Gaudy or ostentatious display: "The antique flash and trash of an older southern California have given way to a sleeker age of cultural hip\u201d ( Newsweek). A flashlight. Instantaneous illumination for photography: photograph by flash.