There's a question on English Language Learners that's been making the rounds recently, it's been on the Hot Network Questions list since January 5 this year and has attracted something like 36,000 views (all credit to tchrist's exhaustive and flawless answer for this extraordinary phenomenon).

I posted an answer, and from a comment, it seems I've done something terribly wrong, but I don't understand what exactly.

Until January 5, I believed that PM, P.M., p.m. or pm was short for post meridian and that it was spelled as two separate words. That's how I've always pronounced it. but it was pointed out to me that the correct Latin spelling is post meridiem. So, I edit the post and add the following reflection

… in English spelled postmeridian [emphasis mine].

Shortly after, a user posted the following comment

'Postmeridian' (single word, no space) may be English (although it is certainly antiquated by 'afternoon') but 'P.M.' is an abbreviation for the Latin phrase 'post meridiem'. There is no 'English spelling' of Latin phrases, there are only translations, but even then 'postmeridian' is actually worse of a translation than 'after noon', because of its archaic status. […]

Was I that wrong to say that ‘post meridiem’ is spelled ‘postmeridian’ in English? Is postmeridian an English translation? That doesn't make much sense to me, it looks very much like a loanword that's been anglicized (?) not translated.

The following definitions are from Merriam-Webster

post meridiem
adjective : being after noon —abbreviation PM
First Known Use: 1647

adjective : occurring after noon : of or relating to the afternoon the postmeridian hours of the day Origin and Etymology
Latin postmeridianus, from post- + meridianus meridian

  • Can someone explain if the original Latin expression consists two words and is spelled “post meridiem”, why is it spelled as a single word in English with a different suffix, dian, postmeridian?

  • Is postmeridian (or post meridian) a bastardization?

  • What is the history of the word postmeridian and its spelling?

Related (paullum) What is the proper name for "AM" and "PM"?


There was a (post-classical) Latin word postmeridianum from the 6ᵗʰ century that meant “after midday” which English first borrowed directly as postmeridian no later than 1583.

The OED says this of its history:

As noun < post-classical Latin postmeridianum the hours after midday, afternoon (6th cent.), use as noun (short for classical Latin postmerīdiānum tempus the time after midday) of neuter of classical Latin postmerīdiānus, adjective; as adjective < classical Latin postmerīdiānus (also in contracted form pōmerīdiānus) (adjective) of or occurring in the afternoon < post after (see post- prefix) + merīdiēs midday (see meridian adj.) + -ānus -an suffix (compare merīdiānus meridian adj.). With use as adjective compare antemeridian adj., and earlier pomeridian adj. With geological senses (see senses A. 2, B. 2) compare premeridian adj. In use as adverb perhaps erroneously for post meridiem adv.

The word postmeridian is now mainly used as an adjective:

Of or relating to the afternoon; occurring after noon or midday.

It also clocks in as a rare noun meaning

The hours after midday, the afternoon. Chiefly fig. Now rare.

Here’s one citation for that use:

1969 Hispanic Rev. 37 208 — The high noon of Charles the Fifth had declined into the somber post-meridian of Philip II.

The word is also sometimes used as an adverb meaning in or during the afternoon. For example:

1996 New Eng. Q. 69 397 — Turkey's ire builds up through the morning and, post-meridian, is vented.

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  • But is "postmeridian" an English translation? Can we call it that? – Mari-Lou A Jan 11 '18 at 12:28
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    @Mari-LouA I wouldn't call it a “translation”, per se. It's just lost its -us suffix, but that happens all the time. It’s a loanword. – tchrist Jan 11 '18 at 12:29
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    post meridiem is a prepositional phrase, normally used adverbially. postmeridianus is the corresponding adjective. postmeridianum is the neuter form of the adjective used as a noun – tchrist Jan 11 '18 at 12:38
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    @Mari-LouA Anglo-Norman French had meridien < Latin meridiem for midday, noon, but this was reinforced by awareness of Latin in English scholars. We ended up spelling that meridian in English after a spell. The OED has a longish write-up about all that business. There’s also meridional meaning south contrasting with septentrional meaning north. – tchrist Jan 11 '18 at 12:41
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    It's nice to have N/S counterparts to oriental and occidental. – Davo Jan 11 '18 at 12:50

I think the following may help complete the discussion about two specular terms:

Antemeridian/Ante meridiem:

“ante meridiem” and “antemeridian” are two different terms. Neither of them is seen much, though, since the first is rarely written out and the second is rarely used at all.

Ante meridiem (two words):

  • The two-word “ante meridiem” is the term that’s abbreviated as “AM” or “a.m.” Like its counterpart, “post meridiem,” it’s seldom written out.

The Oxford English Dictionary classifies “ante meridiem” as an adverb meaning “before midday; applied to the hours between midnight and the following noon.”

  • Standard dictionaries agree that the full phrase is uncommon. The American Heritage Dictionary of the English Language (5th ed.), for example, says “ante meridiem” is “used chiefly in the abbreviated form to specify the hour: 10:30 AM.”

    The term, first recorded in English in 1563, is from Latin: ante (before) and meridiem (midday).

Antemeridian (one word)

The other word, “antemeridian,” is labeled in the OED as a “rare” adjective meaning “of or belonging to the forenoon or ‘morning.’ ”

The word, Oxford says, was derived from the Latin adjective antemeridianus (“of the forenoon”), which in turn comes from ante meridiem.

  • Some standard dictionaries (Longman and Macmillan, for example) don’t have entries for “antemeridian.”

  • One that does, Merriam-Webster’s Unabridged, gives this example of its usage: “antemeridian chores.” Another, Webster’s New World, has “an antemeridian repast.”

  • The OED has only one example for the use of “antemeridian” in a sentence, from an 1865 article in the Daily Telegraph of London: “Every[one] had come out in attire that was decidedly ante-meridian.”


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  • Erm.. not my downvote but the question is about post meridiem Yes, the two forms are closely related, but it's like you completely ignored the title too. – Mari-Lou A Jan 11 '18 at 15:21
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    You've posted quotes without giving any sort of answer yourself (e.g. "This is the answer. Here is my research"). And you've talked about ante rather than post. Oh, and you have typos everywhere, including "ian" in all of your own writing, rather than "iem" in your quotes (I would normally fix typos like that, but it's not worthwhile when the rest of the answer is so lacking). – AndyT Jan 11 '18 at 15:58
  • I've upvoted because the source is good. – Mari-Lou A Jan 12 '18 at 11:18

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