Quick Answer: What Do AM and PM Mean?
AM is short for the Latin word, ante meridiem, meaning “before midday.” PM refers to post meridiem, or “after midday.” To put it simply, AM means before noon and PM means after noon. Thus, 9:00 AM is in the morning and 9:00 PM is in the night.
Introduction
AM and PM are used on clocks, phones, schedules, alarms, appointments, and many more. Most of us use them without giving much thought to the meaning of those letters.
There’s a very simple reason for AM and PM. A 12-hour clock will repeat the same numbers twice a day. There is an 8:00 in the morning and an 8:00 in the evening for example. AM and PM indicate which one they mean.
It sounds easy and for the most part, it is. The only thing that can catch people off guard is typically 12 AM and 12 PM.
What Does AM Stand For?
AM is the Latin term for “before noon. Latin term for “before midday” or “before noon.
AM starts at midnight and continues until just before noon. So these are all AM times:
- The 6:00 AM is early morning
- 9:00 AM is morning
- 11:30 AM is just before noon
A small secret to be known is that AM is not an acronym for ‘morning’! It’s generally used as such because most AM hours are in the morning, but 1:00 AM or 2:00 AM is AM, even though most people would consider that nighttime.
The easiest way to remember it is simply: AM means before noon.
What Does PM Stand For?
PM is another Latin term that means “post meridiem. It is the term for “after midday” or “after noon.”
PM starts at noon and goes on until nearly midnight.
For example:
- 1:00 PM is in the afternoon
- 6:00 PM is usually evening
- 11:00 PM is late at night
PM does not just mean evening! It covers afternoon, evening, and nighttime until midnight.
A good rule of thumb to use is this: if the time is past noon, you are in the PM.
Is 12 AM Midnight or Noon?
This is where it gets a little aggravating since at first 12 AM and 12 PM can seem like the reverse of what is going on.
The rule is:
- 12:00 AM = midnight
- 12:00 PM = noon
So, when it’s 11:59 AM, the next minute will be 12:00 PM.
Frankly, in some situations such as a travel itinerary or appointments, it’s more understandable to use noon and midnight than 12 AM and 12 PM. It removes the guesswork.
| Time | AM or PM? | What It Usually Means |
|---|---|---|
| 6:00 AM | AM | Morning |
| 11:30 AM | AM | Before noon |
| 12:00 PM | PM | Noon |
| 6:00 PM | PM | Evening |
| 11:59 PM | PM | Just before midnight |
| 12:00 AM | AM | Midnight |
Honestly, if you are writing something important like a travel schedule or appointment, using the words noon and midnight can sometimes be clearer than writing 12 AM or 12 PM. It removes the guesswork.
AM and PM vs the 24-Hour Clock
There are some differences in the 24-hour clock since it doesn’t use AM or PM.
It doesn’t repeat the numbers 1 to 12 twice, instead it counts on after noon.
For example:
- 8:00 AM = 08:00
- 2:00 PM = 14:00
- 8:00 PM = 20:00
The time is displayed in both systems. They simply express it in a different way.
The 12-hour clock is used in many daily conversations, such as in the United States, and the 24-hour clock is used in many countries, transportation, healthcare, etc.
Final Thoughts
So, what does AM and PM stand for? AM stands for ante meridiem, which translates to “before noon”. PM signifies after noon (post meridiem).
All you need to remember is this: AM means from midnight till just before noon, and PM means from noon till just before midnight.
As well, if you still find it confusing to remember what 12 AM means versus 12 PM, then here is a little trick: 12 AM is midnight, and 12 PM is noon.