What A.M. and P.M. Stand For

Sun ClockToday I found out what a.m. and p.m. stand for.

And no, it’s not, as my first grade teacher told me, “After Midnight” and “Past Midday”. LIES!!!  Though, funny enough, not really that far off the translated versions of the Latin words for which a.m. and p.m. actually do stand for.

It turns out, a.m. stands for “ante meridiem”, which is Latin for “Before Midday”; p.m. stands for “Post Meridiem”, which is Latin for “After Midday”.

Interestingly, this finally clears up for me one of the interesting quirks of the 12 hour clock system where time counts from 12 a.m. to 1 a.m. and likewise goes from 11 a.m. to 12 p.m., which always seemed odd, but now makes perfect sense given what a.m. and p.m. stand for.

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  • Joe Mama

    Since midnight and noon are the meridiems referred to, it is my understanding that the two are neither AM nor PM, they are just 12:00.

    • Big Papa

      Not just 12, but rather 12 Noon and 12 Midnight.

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  • Interesting info, and when referring to 12:00, I usually write it as either “noon” or “midnight” vs 12:00pm and 12:00am, or 12 noon/midnight. I still get confused which is which!

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  • dalanda derouiche

    i was very astonished how you’ve just discovered the abbreviations a.m and p.m now, i’m arab, i study english as a third language (french is my 2nd language) and our teachers taught us the true full words. and you (english speaker) you’re wrongly taught???????how strange

  • Robert Pittman

    Now it’s finally clear to you what 12:00 a.m. is? There’s no such animal. There is only one meridan and that is noon. Midnight is neither a.m. nor p.m. and neither is noon. It is much more clear and correct to use n. or nn. and m. or mn.

  • Iliyan

    AM and PM are both confusing and long. Americans like to stick with inconvenient measures. Look at all the imperial metrics they still use – terrible! The 24h clock is so much easier. 14:00 vs 2:00 PM – no possible confusion and shorter. Otherwise the military wouldn’t use it :)))

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  • Yer Pal

    As a kid in school one of my classmates taught me an easy way to remember which is AM & PM. When the alarm clock goes off in the morning (usually too damn early); what’s the first thing out of your mouth? “Aaaaaaaagghhh!: There you go – A for mornings. When I asked my classmate what the P in PM stood for; he said “Piss all”.

  • Alistair

    12:00 p.m. And a.m. don’t actually exist because you can’t have a midday that is before or after itself. So that’s why we say noon instead of choicing if it’s an a.m. or p.m. Which also means we say midnight since we don’t have one for noon.

  • Tod

    While I understand the argument of 12:00 being neither am or pm, I think it’s perfectly acceptable to say 12:00 PM for noon and 12:00 AM for midnight as these both start the next 6 hours of the phase.

  • One day I asked my brother what a.m. and p.m. Mean he said well how I remember it it’s at morning and passed morning

  • MARC

    One more thing is you should not add dots “.” while using latin shortcuts. AM instead of A.M. and PM instead of P.M.
    Same goes for eg, ie, etc.

  • Ciaran

    Interesting fact, the English/Scottish/Welsh/Irish druids believed the day began @ 1201am & ended @ 1201 pm, as a death/rebirth of the sun. (from darkness to light, from light to darkness. The rise of the sun at the moons fall, & vise versa)