blacklight

2. A light that gives off mostly ultraviolet rays and very little visible light.

The poster glowed brightly under the blacklight.

3. A device used to check for counterfeit money or hidden marks.

The cashier ran the bill under a blacklight to make sure it was real.

4. A lamp used in clubs and parties to make white clothes and paint shine.

Everyone's white shirts lit up under the blacklights at the party.