As a Noun:
1. A lamp attached to a clock or telephone that you can set to flash so that it wakes you up or gets your attention at a particular time, or flashes when the phone rings. It is mostly used by deaf people. English = flashing-light alarm.
2. A type of clock with a mechanism that can be set to ring, vibrate or flash a light at a certain time. Used for waking a person up. English = alarm clock.