flash on
1. To abruptly turn or go on, as of lights. As the man laughed manically, the lights in the haunted house flashed on, and we all ran out, screaming.
2. To illuminate someone or something. I repositioned my lamp so that it flashed on the things I'd dropped behind my bureau.
3. slang To think of or recall something. It took some time, but we finally flashed on a solution to that problem.
flash on someone or something
[for a light] to shine on someone or something suddenly or in bursts. The orange neon light flashed on John's face, making him look quite strange. The light flashed on the window shade, startling the occupants of the room.
flash on something
Sl. to remember something suddenly and vividly. Then I flashed on a great idea. I was trying to flash on her name, but I couldn't bring it to mind.
flash on
[for a light] to turn on suddenly. The light flashed on and woke us up. When the light flashed on, I had just been getting to sleep.
flash on someone
in. to get angry at someone. Don’t flash on me like that! I didn’t do it!
flash on something
in. to remember something suddenly and vividly. I was trying to flash on it, but I couldn’t bring it to mind.