Flashbulb (noun)

1. A type of light bulb that produces a bright flash of light when an electric current is applied.
2. A momentary emotional response to a shocking event or piece of news, especially one that is well-remembered.

Origin:

Coined in the 1930s, combining flash + bulb.

Examples:

1. The old camera required a flashbulb to take photos in low light conditions.
2. Many people remember exactly where they were and what they were doing when they heard the news of the Kennedy assassination, a typical flashbulb memory.
3. The flashbulbs from the photographers' cameras were so bright that the subjects had to shield their eyes.
4. The flashbulb went off, illuminating the room for a split second.
5. The terrorist attack created a flashbulb memory for many people in the city.