AM

1. When referring to audio or a signal, AM is short for amplitude modulation. AM is a type of broadcast with capability of being broadcast in a wide area, but in a lower quality when compared to FM.
2. When referring to time, am or a.m. is short for ante meridiem, which is Latin for "before the middle of the day" and can also mean after midnight. The a.m. time is between 12:00 PM noon and after 11:59 PM midnight in a 24-hour time clock.
3. Finally .am is also a top level domain.

Also see: FM, PM