{"id":558,"date":"2016-09-06T15:41:39","date_gmt":"2016-09-06T15:41:39","guid":{"rendered":"https:\/\/www.militarytime.us\/?p=558"},"modified":"2022-11-09T17:23:30","modified_gmt":"2022-11-09T17:23:30","slug":"what-do-am-and-pm-stand-for","status":"publish","type":"post","link":"https:\/\/www.militarytime.us\/what-do-am-and-pm-stand-for\/","title":{"rendered":"What Do AM and PM Stand For?"},"content":{"rendered":"
You have likely heard A.M. or P.M. (also seen as AM and PM, a.m and p.m., or am and pm) used to reference the timekeeping in several situations without ever giving much thought to why and where this timekeeping system originated.<\/p>\n
The short answer is A.M. stands for \u201cante meridiem\u201d, which is Latin and depicts the time of day \u201cbefore noon.\u201d P.M. stands for \u201cpost meridiem\u201d, which is Latin and references the time \u201cafternoon.\u201d<\/p>\n
A.M. = Ante Meridiem = Before Noon (12 AM \u2013 11:59 AM)<\/p>\n
P.M. = Post Meridiem = After Noon (12 PM \u2013 11:59 PM)<\/p>\n<\/div>\n
12 Hour Clock<\/th>\n | 24 Hour Clock<\/th>\n<\/tr>\n<\/thead>\n |
---|---|
12:00 (Midnight)<\/td>\n | 0:00 (beginning of the day) or 24:00 (end of day)<\/td>\n<\/tr>\n |
12:01 a.m.<\/td>\n | 0:01<\/td>\n<\/tr>\n |
1:00 a.m.<\/td>\n | 1:00<\/td>\n<\/tr>\n |
2:00 a.m.<\/td>\n | 2:00<\/td>\n<\/tr>\n |
3:00 a.m.<\/td>\n | 3:00<\/td>\n<\/tr>\n |
4:00 a.m.<\/td>\n | 4:00<\/td>\n<\/tr>\n |
5:00 a.m.<\/td>\n | 5:00<\/td>\n<\/tr>\n |
6:00 a.m.<\/td>\n | 6:00<\/td>\n<\/tr>\n |
7:00 a.m.<\/td>\n | 7:00<\/td>\n<\/tr>\n |
8:00 a.m.<\/td>\n | 8:00<\/td>\n<\/tr>\n |
9:00 a.m.<\/td>\n | 9:00<\/td>\n<\/tr>\n |
10:00 a.m.<\/td>\n | 10:00<\/td>\n<\/tr>\n |
11:00 a.m.<\/td>\n | 11:00<\/td>\n<\/tr>\n |
11:59 a.m.<\/td>\n | 11:59<\/td>\n<\/tr>\n |
12:00 (Noon)<\/td>\n | 12:00<\/td>\n<\/tr>\n |
12:01 p.m.<\/td>\n | 12:01<\/td>\n<\/tr>\n |
1:00 p.m.<\/td>\n | 13:00<\/td>\n<\/tr>\n |
2:00 p.m.<\/td>\n | 14:00<\/td>\n<\/tr>\n |
3:00 p.m.<\/td>\n | 15:00<\/td>\n<\/tr>\n |
4:00 p.m.<\/td>\n | 16:00<\/td>\n<\/tr>\n |
5:00 p.m.<\/td>\n | 17:00<\/td>\n<\/tr>\n |
6:00 p.m.<\/td>\n | 18:00<\/td>\n<\/tr>\n |
7:00 p.m.<\/td>\n | 19:00<\/td>\n<\/tr>\n |
8:00 p.m.<\/td>\n | 20:00<\/td>\n<\/tr>\n |
9:00 p.m.<\/td>\n | 21:00<\/td>\n<\/tr>\n |
10:00 p.m.<\/td>\n | 22:00<\/td>\n<\/tr>\n |
11:00 p.m.<\/td>\n | 23:00<\/td>\n<\/tr>\n |
11:59 p.m.<\/td>\n | 23:59<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\nAdoption of AM and PM<\/h3>\nThere are two primary timekeeping systems used today in the world. The first and most popular is the 24-hour clock on which military time is based. The second and most popular in the United States is the 12-hour timekeeping system.\u00a0 The twelve-hour timekeeping system is used by the United States, Australia, Malaysia, New Zealand, Columbia, Philippines, Many areas of Canada, and informally in other countries.<\/p>\n AM and PM are depicted differently in English, Greek, Portuguese, Russian, and Hebrew<\/a> often times using special characters, changing the order of the hour and minutes, or using oral descriptions after the stated time (ex: 9 in the morning)<\/p>\n The use of a.m. and p.m. dates back to 1500 B.C. with the invention of the sundial in ancient Egypt. The Egyptians are credited for dividing the day into 24 parts or \u201chours.\u201d\u00a0 A sundial, as it implies in its name, uses the sun’s positioning in the sky to determine time. 12-hour timekeeping is notated with Noon (12 p.m) as the meridian (center) instead of midnight (12 a.m) as the sundial would not work in the middle of the night. The creation of AM (ante meridiem or before noon) and PM (post meridiem or afternoon) was necessary to describe how close the sun was to the meridian (12 Noon). Since sundials were invented more than 1,000 years before the notation of zero, the number assigned to the middle of the day was 12.<\/p>\n |