In modern day lingo, we often read and hear phrases like "50 cycles a second" or "60 words a minute" or "30 kilometers an hour". When did English first start using "a(n)" like this? Googling "a definition" claims that the usage of "a" as an article began in Middle English, but I doubt that this definition predates Modern English.

I find it plausible that "per" may have reverted to just a schwa in some dialects, but I have no evidence for this hypothesis other than a gut feeling.

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    I'd rather say that at some point “per” just got omitted, "30 kilometers per an hour" > "30 kilometers an hour".
    – Yellow Sky
    Dec 9, 2021 at 2:07
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    @YellowSky except one doesn't say "per a(n)", one either says "per" or "a(n)"
    – Tristan
    Dec 9, 2021 at 10:10
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    I'd like to question the presupposition that "per" is older or more original usage than "a". Per is a word borrowed from Latin by scientific or scholarly usage. People on the market place probably (not references of researched, therefore a comment) used "a" all the time and demotic usage wins over scientific usage in this case.
    – jk - Reinstate Monica
    Dec 9, 2021 at 11:02
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    Using a simple indefinite or definite form is quite a common way to express ‘per’ in many languages, so there’s nothing strange about it in English. It doesn’t come from ‘per’ being reduced, though (that would be quite an unusual reduction), but from the well-established reduction of the preposition ‘on’. As @jk says, this is not recent: it happened in late Old English or early Middle English. In OE, we have seofen syðan on daig ‘seven times [in] a day’ with on, but already by around 1200, we have the sunne arist anes a dai ‘the sun rises once a day’ with a. (Quotes from OED.) Dec 9, 2021 at 11:15
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    @JanusBahsJacquet Now that the question is in the right place, your comment is indeed at least a very good basis for an answer.
    – Andrew Leach
    Dec 11, 2021 at 13:19

1 Answer 1


Actually, your question should be asked the other way around: "when did per become a synonym for a?", since this use of a is much older. And the answer, according to the OED, is around 1400.

The OED says that a was used in this way in Old English, but originaly just for intervals of time. From the OED's citations it seems like it wasn't used for anything but time until the 16th century (sixty tyme a day, twyes a wooke, þries or foure siþes a ȝeere ...). In Old English this was originally the same word as on, but in late Old English and Early Middle English some uses of on, including this one, lost the /n/.

The first easily comprehensible citation the OED gives is circa 1200:

The sunne..arist anes a dai.

The first citation they give for per is in 1399. And for per, in their first 150 years of citations, it seems only to be used for prices (e.g., russet cloth per yard 15 pence). Here is one from 1413:

I pray and chearge..þat on my stynkyng careyne be neiþer laid cloth of gold ne of silke but russet cloþ per ȝerd xv d.

One more comment ... it appears that, given their respective fields of use, before the 16th century they would only have been synonyms in expressions like "a penny a day".

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    I wonder if the original intention behind a phrase like "per yard" was "according to the number of yards," and then only later did the interpretation change from "according to" to "for each." Dec 11, 2021 at 19:15
  • @TannerSwett "a yard" cannot mean "according to the number of yards," as "a" = one. In "It is $6 a yard, "a yard" would have been in the dative in OE and would have formed the same modifier as it does now.
    – Greybeard
    Dec 11, 2021 at 19:23

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