AM: Anti Meridiem, PM: Post Meridiem
Do you ever wonder why we denote time in terms of AM and PM? What do AM and PM stand for? From where did this way of denoting time originate? If the answer to any of these questions is yes, then you have reached your destination. Before understanding what AM and PM mean in the context of the 12-hour clock system, it is important to understand the 12-hour clock system first. The 12-hour clock system is a time convention used mainly in most analogue and digital clocks. This is a popular way to read time in most English-speaking nations and the then British colonies. The 12-hour clock convention is the one in which 24 hours are divided into two periods- AM and PM.
Full form of AM and PM in detail
AM and PM are both Latin terms used to represent time in the 12-hour convention. A.M. stands for Ante Meridiem and P.M. stands for Post Meridiem. Meridiem is a Latin word that basically means midday (Meri means mid and Diem means day). Hence, Ante Meridiem means “before midday” and Post Meridiem means “after midday”. In the 12-hour clock system, AM and PM are used before noon and afternoon respectively.
Fun Fact: It might be interesting to know that a 12-hour clock system is not a new concept. Even during ancient times, Egyptians and Mesopotamians used it in primitive forms. For instance, the Egyptian sun-dial clock for daytime use and Egyptian water clock for night-time use were found in the tomb of a Pharaoh.
To understand this system of denoting time, you can simply look at it as two different time zones of 12 hours each that represent day and night. Basically, 24 hours are divided into two time zones (before noon and afternoon) that last for 12 hours each. The first 12-hour duration starts from midnight and lasts till noon which is called by AM (12 AM to 12 PM). The second 12-hour duration begins from noon and lasts till midnight denoted by PM (12 PM to 12 AM).
Let us understand this with the help of examples. When someone says it's 9 AM, it means that the time is 9 O'Clock in the morning. So, from 12 at night to 12 in the noon (exactly at 11:59 AM), it represents the day clock. Similarly, when someone says it is 9 PM, it means that the time is 9 O'Clock in the evening. Hence, from 12 in the noon to 12 at midnight (precisely,11:59 PM), it is the night clock.
These conventions are set up to understand time in a better manner. Suppose, if someone says that he/she will meet you at 8 O'Clock tomorrow, it will be confusing whether that person meant 8 in the morning or 8 in the evening. To avoid such time-related confusion, the 24-hour daytime is divided into two different cycles of 12 hours each. Moreover, another confusion that is quite common is to understand 12 AM and 12 PM, also these are not technically correct. There is no such thing as 12 AM or 12 PM. It is actually called 12 in the noon (12 PM) and 12 at midnight (12 AM). To avoid confusion, many companies including some airlines and banks, etc. use 12:01 AM to mark the beginning of an event that starts with the onset of the day and 11:59 PM to mark the end of any event that ends with the day.
In some countries like the USA and Canada Military timing is used which works on the 24-hour clock system. This system completely rules out the possibility of using AM and PM, thereby eliminating confusion altogether. Here, the entire day is divided into 24 hours. It is important you know both the systems and understand how they can be interconverted. Comparison between the two can be understood by the following table:
Time is an entity that has generated curiosity among Humans since time Immemorial. But the Human mind has always been troubled with the way time and related concepts work. To understand time better, you can refer to Vedantu’s explanation of time. It will help you a lot in subjects like mathematics and geography.
The concept of AM and PM is not just relevant in academics but also holds a lot of significance in daily life. Vedantu hopes you enjoyed reading this article on AM and PM, learnt something new and also got all your doubts cleared about the same.
FAQs on What is the full form of AM and PM
1. How to convert the 12-hour time format to 24-hour time format?
Converting the 12-hour format to the 24-hour format is fairly simple. The 24-hour clock is a time convention that runs from midnight to midnight, from hour 0 to hour 23. If the time is 12 AM (12 at midnight), it is simply 0:00 hours. Then, 1:00 AM is denoted as 1:00 hours and so on till 12 PM (12 in the noon) i.e. denoted as 12:00 hours. From 1:00 PM to 11:59 PM, add 12 hours. For example, if the time is 2:00 PM, you can say (2+12= 14) the time is 14:00 hours in 24-hour time format.
2. Is it 12 midnight AM or PM?
For many people, one of the most confusing things about time is to understand whether 12 midnight is AM or PM. Similarly, what is 12 at noon called? As per the convention, 12 AM denotes midnight and 12 PM denotes noon. However, to avoid confusion, it is better to use 12 noon and 12 midnight. 'Noon' denotes 'mid-day' or 12 o’clock during the day. ‘Midnight’ denotes 12 o’clock (or 0:00) during the night. You can also use the 24-hour clock system, where 12:00 is noon and 00:00 (or 24:00) is midnight.
3. Is it necessary to capitalize AM and PM?
The abbreviations a.m. and p.m. are generally written in lower cases when they are part of a running text. But it is not a rule as such. They can be capitalized as well in the form of AM and PM. The only care that one needs to take is that when capitalizing, letters are not followed by a period. When lowercase, letters are followed by a period (10 a.m. or 10 p.m.). One may consider using small caps when using them in running text to improve readability.
4. I often tend to get confused between AM and PM, what should I do?
You are not the only one who gets confused between AM and PM. to do away with this confusion Vedantu has brought this information to help you understand these full forms with utmost clarity. Read this piece of information as many times as you need and try to apply them in daily practice. Apply these whenever you look at your watch or when some ask you the time. To help you with many such other abbreviations, Vedantu has dedicated an entire web page to full forms.
5. Is there any alternative to the AM and PM system of denoting time?
Though AM and PM is a very easy way of telling time some people find it confusing. This confusion arises due to the repetition of denominations and the use of AM and PM. to avoid this confusion, you may refer to the 24-hour clock system or military time. In this convention, the day is divided into 24 hours from midnight to midnight. 12 o’clock midnight is referred to as 00:00, 1 o’clock at night is referred to as 01:00, 12 o’clock noon is referred to as 12:00, 1 o’clock during the day is referred to as 13:00, 11 o’clock at night is referred to as 23:00, so on and so forth. You may refer to this forum by Vedantu to get further details about the 24-hour clock system.