phosphorescent gas
nounUK /ˌfɒsfəˈrɛsənt ɡæs/
US /ˌfɑːsfəˈrɛsənt ɡæs/
A gas that glows in the dark after the light is turned off.
The old clock had hands painted with phosphorescent gas so you could read the time at night.
OTHER MEANINGS
2. A gas that gives off light without heat, often used in signs and markers.
The exit sign used a phosphorescent gas to stay visible during a power cut.
3. A gas that continues to shine after the source of energy is removed.
Scientists studied the phosphorescent gas to understand how it stored light energy.
4. Any gas mixture treated with a glowing substance for safety or decoration.
The toy stars were filled with a harmless phosphorescent gas that glowed at bedtime.