a device for awakening people who don't have small children
a device for waking people up who don't have small kids
mechanism bundled into a clock to ring or vibrate at a set time.
The earliest mechanical clocks were alarm clocks intended for the use of monks so that services could be held at the appointed ecclesiastical hours; all modern alarm clocks are descended from these monastic alarms
Alarm can be set to alert at a pre-selected time.
An alarm clock is a clock that is designed to make an alert sound at a specific date and/or time. The primary use of these clocks is to awaken people from their sleep in order to start their days in the mornings, but they are sometimes used for other reminders as well. To stop the sound, a button or handle on the clock needs to be pressed, and some stop automatically after a few minutes if left unattended.