We find "Working hours – 10:00 AM to 05:00 PM" written on the front door of the offices, and some stores. We also see these two abbreviations on our train or flight or bus tickets written next to the time of arrival or departure. We often use these two abbreviations while telling the time on the clock but we never bother to know what do these two abbreviations i.e. AM and PM stand for.
What AM and PM stand for?
AM and PM are two commonly used Latin phrases. AM is an abbreviation for ante meridiem which means "before noon" and it is used on the twelve-hour clock to indicate times during the morning. AM represents the time right after midnight to noon.
PM is an abbreviation for post meridiem, a Latin phrase which means "afternoon". It is used on the twelve-hour clock to indicate times during the afternoon. PM represents the time right after noon to midnight. It is "meridiem" with "em" not "meridian" with "an" at the end.
- "What time the Prime Minister is coming in the city for Swachh Bharat Abhiyaan?"
- "At 05:00 AM"
- "Okay, and what time he will be departing from here?"
- "Around 03:00 PM"
Here, 05:00 AM means 5 o'clock early in the morning and 03:00 PM means 3 o'clock in afternoon.
Denoting am and pm
You can denote ante meridiem as am, a.m., AM, or P.M. and post meridiem as pm, p.m., PM, P.M. These phrases can be used in following ways:
- 05:00pm or 05:00p.m. or 05:00PM or 05:00P.M.
- 5:00pm or 5:00p.m. or 5:00PM or 5:00P.M.
- 5pm or 5p.m. or 5PM or 5P.M.
- 05:00 pm or 05:00 p.m. or 05:00 PM or 05:00 P.M.
- 5:00 pm or 5:00 p.m. or 5:00 PM or 5:00 P.M.
- 5 pm or 5 p.m. or 5 PM or 5 P.M.
Yet, there is always confusion when we think what abbreviation should be used for noon and midnight. We generally designate noon as 12 PM and midnight as 12 AM in 12-hour clock system.
Now if your friend says,"Hey, pick me up at the airport at 12 AM." Would you go at midnight between today and tomorrow or 24 hours later to pick him up?
The solution for the confusion
To overcome this confusion either your friend should ask you to pick him up at 12:01 AM tomorrow or 24-hour clock system should be used. Here, 0:00 refers to midnight (beginning of the day).