I would just like to know, what does A.M. & P.M. stand for in the terms of morning and night ?

Answer 1

' Ante - Meridian ' and ' Post - Meridian '

Answer 2

The 12-hour clock is a timekeeping convention in which the 24 hours of the day are divided into two periods called ante meridiem (a.m., Latin from most idiomatic to most literal "forenoon" "before noon", "before midday", "before the middle of the day", "before the meridian", and "before the middle day") and post meridiem (p.m., Latin for "afternoon", "after noon", etc.) Each period consists of 12 hours numbered 12 (acting as a zero), 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11. The a.m. period runs from midnight (inclusive) to just before noon (exclusive), while the p.m. period runs from noon (inclusive) to just before midnight (exclusive). The most common convention is to assign 12 a.m. to midnight and 12 p.m. to noon, defining both half days to have a closed (inclusive) beginning and open (exclusive) end.


History and usage
The 12-hour clock originated in Egypt. However, the lengths of their hours varied seasonally, always with 12 hours from sunrise to sunset and 12 hours from sunset to sunrise, the hour beginning and ending each half-day (four hours each day) being a twilight hour. An Egyptian sundial for daylight use[1] and an Egyptian water clock for nighttime use found in the tomb of Pharaoh Amenhotep I,[2] both dating to c. 1500 BC, divided these periods into twelve hours each. The Romans also used a twelve-hour clock: the day was divided into twelve equal hours (of, thus, varying length throughout the year) and the night was divided into three watches.

The Romans numbered the morning hours originally in reverse: for example, "3 a.m.", or 3 hours ante meridiem meant "three hours before noon", compared to the modern meaning of "three hours after midnight".

Early medieval clock faces used the 12 hour numbering scheme (using Roman numerals), but showed both a.m. and p.m. sequences simultaneously. This is known as the Double-XII system, and can be seen on surviving medieval clock faces, such as those at Ottery St Mary, Wells, and Venice.

Today, most analog clocks use the 12-hour clock dial, where the hour hand (shorter and sometimes thicker) commonly rotates once every 12 hours. These are used even in cultures where the 24-hour notation is otherwise preferred. Some 12-hour dials show the numbers 13 to 23 written inside the primary 1 to 12 ring.

Although it has largely been replaced today by the 24-hour notation around the world, especially in written communication, the 12-hour notation with a.m./p.m. suffix is common in some parts of the world.

Answer 3

ante meridian (before midday) and post meridian (after midday), thus making it very annoying when people try to make sense of the impossibilities "12 a.m." and "12 p.m." which should simply be written "noon" and "midnight."

Answer 4

In Spanish it means "antes del meridiano" Before meridian" and "despues del meridiano" after meridian, but in English I think it must be in Latin.

Answer 5

AM= ante meridian, before noon
PM= post meridian, after noon

Answer 6

It is Latin

ante meridiem means BEFORE noon
post meridiem means AFTER noon

Answer 7

a.m ante meridiem

p.m post meridiem

Answer 8

ante meridien
and
poste meridien