The AM and PM abbreviation is often used to describe the time of day, but what does AM PM stand for? What is the meaning of AM and PM?
A.M. stands for ante meridiem, which is Latin for “before midday”.
P.M. stands for post meridiem, which is Latin for “after midday”.
Although the AM/ PM system arose long before the Romans, the Romans were those who named the hours as AM/ PM and spread the use of these terms throughout their colonies around the world. These Roman terms have amazingly been retained to this day, and are still used over 2000 years later.