A.M. means ‘ante meridiem’ (Latin), which means ‘before midday’ and P.M. is ‘post meridiem’ which means ‘after midday’. The 24 hours of the day are divided into these two time-periods: A.M. which starts at midnight and P.M. which begins at noon. The Meridian is an imaginary line joining the north and south points of our horizon. As the sun crosses the meridian, it is noon (afternoon, P.M.) at that place. Before this, when the sun is still east of this imaginary line, it is morning (A.M.). In ancient times, the Egyptians and the Mesopotamians recorded time using sundials during the day and water clocks at night. They were the first to use the concept of A.M. and P.M.
What do AM and PM Mean?
