Meaning of a.m. AND p.m

Dear teachers,

a.m. means from after midnight (24h1second) to midday(12h).
p.m. means from after midday(12h1second) to midnight(24h).

Is it right?

Tung Quoc



I’ve never heard a rule for a.m. and p.m. stated in seconds, only in minutes. :lol:

The rule I’ve always heard is:

a.m. begins at 00:00 and continues until 11:59
p.m. begins at 12:00 and continues until 23:59

So, if you schedule a teleconference that is to begin precisely at noon (and not one single second later :lol:), the exact starting time would be 12 p.m.

But because people are often confused about the exact starting and ending times for a.m. and p.m., it is often better and clearer to write 12 midnight and 12 noon rather than 12 a.m. and 12 p.m.



(Just to add a word :))

Initially (as they come from Latin):
Ante Meridien and Post (not past!) Meridien

and just Meridien for both noon or midday

Hi Tamara, I think you’ve made a typo
ante meridiem and post meridiem

Hi Amy,
Me too,I didn’t understand what Quoq had written in brackets about 1second :shock: I thought it was his typo.

Hi, Pamela, you’re right. My morning (a.m. :)) posts written in ‘pure Latin’ are quite impressive, as usual… :slight_smile:

Dear Amy

Like you used the term ending time, could I also use ending date etc?

1- The ending date of the topic is 01-05-2006.

I mean, could I use ending as a normal adjective?

Do we agree?



Hi Tom

I see no reason not to say “ending date” but using it wiith the word “topic” seems a little odd. Why did you want to talk about the ending date of a topic? What exactly did you have in mind?


AM = Ante Meridian (Latin, Before Midday)
PM = Post Mereidian (Latin, After Midday)