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Important notice

Good news! We have updated our writing tools. Writing Tips and The Canadian Style have been combined to create a new tool called Writing Tips Plus.

Don’t forget to update your bookmarks. Within a few weeks, Writing Tips will no longer be available.

To begin your search, go to the alphabetical index below and click on the first letter of the word you are searching for.

a.m., p.m.

The abbreviations a.m. and p.m. stand for the Latin ante meridiem and post meridiem, meaning before and after midday. These abbreviations should be used only with numerals (e.g. 9:00 a.m. or a.m., not nine a.m.).

In Canada, these abbreviations are usually written in lower case, with periods and with no internal spacing. A non-breaking space should be used between the time and the abbreviation a.m. or p.m.

  • The Prime Minister’s speech will be broadcast at 8:05 p.m. on all stations.

Regular capitals (A.M., P.M.) or small capitals (A.M., P.M.) are acceptable alternatives in headlines, lists or tables written in upper case.

  • Headline: ECLIPSE AT 11:15 A.M. TODAY

Never use a.m. or p.m. with the expression o’clock or with the words morning, afternoon, evening or night.

  • Sarah doesn’t answer the phone after ten o’clock (not ten p.m. o’clock).
  • The lecture began at 4:30 p.m. (or 4:30 in the afternoon, but not 4:30 p.m. in the afternoon).

If the 24-hour clock is used, a.m. and p.m. are unnecessary and incorrect.

  • The next flight to Thunder Bay leaves at 14:45 (or 2:45 p.m., not 14:45 p.m.).

For more information on how to write the time of day, see TIME OF DAY, ELAPSED TIME.