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NPL
npl.co.uk › resources › q-a › is-midnight-12am-or-12pm
Midnight - is it 12am or 12pm? - NPL
There are no official standards ... ‘pm’ stand for ante meridiem and post meridiem – Latin words meaning ‘before the middle of the day’ and ‘after the middle of the day’....
time counting system, divided into two parts: AM and PM
exeter cathedral astronomical clock
The 12-hour clock is a time convention in which the 24 hours of the day are divided into two periods: a.m. (from Latin ante meridiem, translating to "before midday") and p.m. (from … Wikipedia
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Wikipedia
en.wikipedia.org › wiki › 12-hour_clock
12-hour clock - Wikipedia
2 weeks ago - The 12-hour time convention is common in several English-speaking nations and former British colonies, as well as a few other countries. In English-speaking countries: "12 p.m." usually indicates noon, while "12 a.m." means midnight, but the reverse convention has also been used (see § Confusion ...
Discussions

Is 12 PM at noon? How is that when 11 am is in the morning And 1 am is in the night. Where did the 12 am go?
12pm is noon, 12am is midnight. More on reddit.com
🌐 r/EnglishLearning
156
96
August 21, 2024
meaning - What time is 12.00pm? - English Language & Usage Stack Exchange
We were well aware of the 12am / 12pm potential for confusion when I taught maths, and (in line with our exam board) insisted on the logical 12 noon/midday // 12 midnight. But we warned the pupils that they might encounter 12 pm, when it should by convention mean 12 noon, but might be being ... More on english.stackexchange.com
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November 14, 2013
abbreviations - Use of “12 m.” for noon and “12 p.m.” for midnight - English Language & Usage Stack Exchange
The problem with that logic is that it doesn’t fit with how most people refer to noon and midnight. 12 PM usually means noon, which is obviously not the twelfth hour in the period between noon and midnight; and 12 AM usually means midnight, which is equally obviously not the twelfth hour ... More on english.stackexchange.com
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What does "12pm" mean?
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11
1
October 7, 2020
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Royal Museums Greenwich
rmg.co.uk › stories › time › noon-12-am-or-12-pm
Is noon 12 am or 12 pm? | Royal Museums Greenwich
When most people say 12pm, typically they're talking about the middle of the day: 12 noon. When they say 12am, they normally mean 12 midnight. While some people follow this convention, technically it's not quite right – as you'll see from ...
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EnglishClub
englishclub.com › efl › articles › vocabulary › 12am-12pm-whats-the-difference
12am & 12pm – What’s the Difference?! | EnglishClub
Where the problem always arises is when you go to make a reservation online and it asks 2; AM or 12:00PM, so of the minute before noon is 11:59 AM, Then noon must be 12:00 PM ... In case of doubt I recommend always to use the 24-hour clock, which means writing the time with four digits, like: 01.20 (The leading zero indicates that this is the 24-hour clock and must mean 1.20am in the morning.
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TimeAndDate
timeanddate.com › time zones › am and pm
AM and PM: What Do They Mean?
This is the 12-hour period from midnight to noon. PM means after noon.
Find elsewhere
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Stack Exchange
english.stackexchange.com › questions › 137624 › what-time-is-12-00pm
meaning - What time is 12.00pm? - English Language & Usage Stack Exchange
November 14, 2013 - That leaves 12:00 a.m. to be used ... has a usage note on this topic: "By convention, 12 AM denotes midnight and 12 PM denotes noon....
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Encyclopedia Britannica
britannica.com › technology › engineering › mechanical engineering
What Do AM and PM Stand For? | Time, Clock, History, & Facts | Britannica
December 31, 2025 - This system is based on the position ... am stands for ante meridiem, “before midday” in Latin, while pm means post meridiem, or “after midday.”...
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Cuemath
cuemath.com › measurement › am-pm
AM and PM - Meaning, Full Form of AM PM | Relation with 24-Hour clock
The abbreviation 'AM' stands for ... 11.59 in the morning. PM stands for Post-Meridiem, which means it is the time after the meridian line has crossed the Sun, or, the time between noon and 11.59 at night. The 12-hour clock method defines all 24 hours of the day using the numbers ...
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QuillBot
quillbot.com › home › is 12 p.m. afternoon?
Is 12 p.m. afternoon?
December 16, 2024 - 12 p.m. is the start of the afternoon. It is a point in time that is also called “midday” or “noon” and is expressed as 12:00 in 24-hour clock. It comes
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Timewatch
timewatch.com › home › am pm explained. is noon 12am or 12pm? why are there 24 hours in a day?
When is 12:00AM Tuesday? AM PM Time Format Explained?
October 31, 2025 - When is 12:00AM Tuesday? Is it midnight on Monday, Tuesday noon, or Tuesday midnight? “It’s Tuesday morning!” you may say confidently, but is it? We asked 100 people and received three answers to this question.
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Reddit
reddit.com › r/nostupidquestions › what does "12pm" mean?
r/NoStupidQuestions on Reddit: What does "12pm" mean?
October 7, 2020 -

I have the following deadline from a class:

"All reading posts are due the day before class at 12pm"

"i.e. if you are writing a reading response for Tuesday's class, it is due by 12pm Monday."

Does it mean that it is due at 12:00 noon, or 12:00 midnight?

I was assuming midnight, but because there are marks for a late submission, I really don't want to be wrong about this!

Edit: Thanks all, saved me! I'll save my response for another week then, since we can submit them rather flexibly.

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The Guardian
theguardian.com › notesandqueries › query › 0,,-1752,00.html
Is midnight 12pm or 12am? | Notes and Queries | guardian.co.uk
Skip to main content · EITHER, since it is both 12 hours before and after noon. The real question is: what is mid-day
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Quora
quora.com › What-is-12-am-and-12-pm
What is 12 am and 12 pm.? - Quora
To me, it is very clear that 12 am is midnight, and 12 pm is noon. 12 am is the instant the day changes.
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DoodleLearning
doodlelearning.com › home › maths & english help for parents › what does am and pm stand for?
What does AM and PM stand for? | DoodleLearning
October 20, 2023 - AM refers to the first 12-hour period while PM refers to the second. Twelve-hour time uses AM and PM to distinguish between the first half of the day and the second half. Meanwhile, 24-hour time doesn’t require distinguishing markers because hour numbers aren’t repeated.
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B made a technical error, in both her original deadline specification and in her follow-up message to you, to imply that “12pm” has a well-defined meaning. It does not. 12:00 noon is neither ante meridiem (before noon) nor post meridiem (after noon); it is exactly noon, and it should be referred to as such (http://www.npl.co.uk/reference/faqs/is-midnight-12-am-or-12-pm-faq-time).

Likewise, 12:00 midnight is exactly midway between one noon (i.e., meridiem) and the next, so one might argue that it has equal right to be called either am or pm. Midnight is also neither an “am” nor a “pm.” You can remove all ambiguity by referring to it as midnight.

You can usually infer from context whether a speaker means 12n or 12m when she says “12pm,” which is surely why most people continue to do it. But in the case of your deadline, I’m with you: I might also have assumed that a more likely time for a deadline would be midnight.

I think that both your note and B’s response were respectful and polite. You should be glad you asked. Asking saved you and B from missing your schedules. Had her response been different (she could easily have answered in the opposite way, because of the undefined-ness of “12pm”), it might have saved you from mistakenly prioritizing your application over something more urgent.

There are some fun stories on this noon/midnight topic at http://www.theguardian.com/notesandqueries/query/0,,-1752,00.html. Search for the string “3.07” for one that I found particularly intriguing.

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I agree with @TessellatingHeckler that B is being polite (as well as brief) in her response (she probably has a lot to do).

She says please, thanks, and Kind regards. If she had been less brief, perhaps she would not have sounded brusque to you.

Hi A.

Absolutely! For future reference, 12pm is 12 noon, and 12 midnight is 12am.

So, yes, the form is due by 12 lunchtime today, please.

Thanks, and Kind regards,

B

Imagine how many times she might have answered this question! Yet she is polite. (Had she said "sincerely", it might have been worse.) No harm done on either end.

(For future reference, imagine setting a digital alarm clock for an important event in the morning. A.M. begins at 12:00 at night, and ends with 12:00 noon - just as B pointed out.)

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Quora
quora.com › Why-is-noon-12-PM-instead-of-AM-when-it-followed-9-10-11-AM
Why is noon 12 “PM” instead of “AM” when it followed 9, 10 & 11 AM? - Quora
Well 12 noon is the instant that AM becomes PM. AM stands for AnteMeridian and PM stands for PostMeridian. Ante- is a prefix meaning before and post- is a prefix for after. The meridian is an imaginary line in the sky that runs from the northern ...