What does the AM & PM stand for when telling time?

Answer 1

A.M.

before midday (ante meridiem)

P.M. also p.m. or P.M.
abbr.

after midday(post meridiem)

USAGE NOTE By definition, 12 A.M. denotes midnight, and 12 P.M. denotes noon, but there is sufficient confusion over the meanings of A.M. and P.M. when the hour is 12 to make it advisable to use 12 noon and 12 midnight where clarity is required.

Answer 2

AM = ante meridiem (a.m., from Latin, literally "before midday")

PM = post meridiem (p.m., "after midday")

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., from Latin, literally "before midday") and post meridiem (p.m., "after midday"). 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 to noon, while the p.m. period runs from noon to midnight. The most common convention is to assign 12 a.m. to midnight (at the beginning of the day) and 12 p.m. to noon, defining both half days to have a closed (inclusive) beginning and open (exclusive) end. 12 noon and 12 midnight can more clearly express these times (except that for midnight one may need to also specify whether it is the midnight at the beginning or the end of the day in question).

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 12 hours each. The Romans also used a 12-hour clock: the day was divided into 12 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".

Answer 3

AM = Ante Meridian; PM = Post Meridian
where meridian is the point where the sun is overhead (aka "noon"_; "ante" means before (the noon line); and "post" means after (the noon line)

Answer 4

AM = Ante Meridian; PM = Post Meridian

Answer 5

those are abbreviations for latin expressions.. am stands for ante meridian (meaning until eventually now meridian or until eventually now midday (whilst the sunlight is optimal in the sky) pm stand for positioned up meridian (meaning after meridian or after midday)

Answer 6

AM: After midningt and before noon Example 8AM = 8 in the morning

PM: noon to midninght Example: 9PM = 9 at night

Answer 7

am = ante meridiem "before midday"
pm = post meridiem "after midday"

Answer 8

AM means between midnight and noon, or before noon.
PM means between noon and midnight, or after noon.

Answer 9

AM- ante meridian
PM- post meridian

Answer 10

after midnight and past midday