what am and pm stands for

AM and PM Full form in Time, Meaning, History, facts | What is Ante Meridiem and Post Meridiem

Looking for what does am and pm stands for in time.

See, there are a lot of abbreviations we use in daily life, without knowing what history is behind them.

Today, we will learn, am and pm full form in time, it’s meaning and history behind it.

See, English speaking folk have been using AM, PM for ages as a prefix in time.

Today, I will take you through, how, these initialism came into fashion.

So, before going to a long debate, first, let me make you familiar with what is the full form of am and pm quickly.

AM and PM full form in time

AM and PM are the abbreviations of Latin word, Ante Meridiem
Post Meridiem.

What is Ante Meridiem and Post Meridiem

Ante Meridiem stands for before Mid Day (before Noon) and Post Meridiem for after Mid Day (After Noon).

See, in 12 hour clock time, these prefixes are used to divide 24 hours into two halves.

lets understand it better with below table.

InitialismFull Form (Letin)English Time
AMAnte Meridiem Before Mid Day (Before Noon)12:00 (Mid Night) to 11:59 (Mid Day)
PMPost Meridiem After Mid Day (After Noon)12:00 (After Noon) to 11:59 (Mid Night)

Lets have better Idea with this below Info Image

am and pm full form in time

These abbreviation, have been being used in English speaking country, like UK, USA and their colony since long.

In Certain European countries still 24 hour time slot is used.

Sol lets understand in detail.

24 hour of a day are divided into 12 hour halves.

First halves starts from mid night 12:00 to Mid Day 11:59 and second halves from 12:00 Mid day to 11:59 Mid night.

for example, If someone says, I will go to school at 6 ‘0’ clock. Here it is not clear whether, morning 6 or evening 6.

So in order to differentiate it prefix AM and PM are used.

If He intends to go to school in the morning. The sentence must be, I will go to school at 6 a.m.

History of AM and PM

In 1500 BC, Mesopotamia and ancient Egypt used a 12-hour clock.

There were two separate man-made watches called ‘sundial’ for daytime and a ‘water clock’ for night time use.

In Ancient times, Man used to use sun position to know the time in the day and moon position for the night.

Thus whole 24 hour day was divided into two half.

Romans also used a 12 hour clock.

Some Facts about AM and PM

In the 21st Century, the 12-hour clock is dominant in written or spoken language in most countries.

As we earlier discussed, the 12-hour system was used by English speaking people.

Hence, the UK and its colonies such as India, USA, Ireland, Australia, New Zealand Pakistan, Bangladesh, Malaysia, Malta, etc started to use it.

But in certain countries such as Europe and Latin America, the 12-hour system is used in speaking and 24-hour clock is used in writing.

However in speaking, morning, afternoon evening is used with time for better understanding. For example 3 ‘o’clock in the morning,

In most countries, computers by default show the time in 24-hour notation. Mircosoft Windows, Unix, Linux, and macOS are few examples.

Time 12 comes in the night or in a day. It becomes confusing sometimes to understand 12 am and 12 pm. To make it quick striking 12 night and 12 noon are used.

In insurance and airline company use 12:01 to start an event in the day time and 11:59 to end an event at night.

Types of writing AM and PM

S.NCountryWritten Style
1.Latina.m. and p.m.
2.English, Spanisham pm, AM PM, A.M. P.M.
3.Greekπ.μ. and μ.μ

How to Remember

As ‘A’ comes first in alphabet before ‘P’. Hence AM comes first in a day from 12 am (Midnight) to 12 pm (Mid day).

PM comes from 12 pm (Mid day) to 12 am (Mid night)


AM – Ante Meridiem (Latin), Before Mid Day (English)

PM – Post Meridiem (Latin), After Mid Day (English)

I hope, you must have liked my effort to educate you about the meaning and full form of AM and PM.

If you like my effort, share this blog post to your social media account as a compliment.

Further Reading

7 different ‘portal’ full form

LGBTQ full form and other variants of it

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