per

¹ American  

[pur, per] / pɜr, pər /

preposition

1. for each; for every.

   Membership costs ten dollars per year. This cloth is two dollars per yard.

2. by means of; by; through.

   I am sending the recipe per messenger.

3. Also according to; in accordance with.

   I delivered the box per your instructions.

   He managed to monopolize the meeting, per usual.

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adverb

1. Informal. each; for each one.

   The charge for window-washing was five dollars per.

per- ² American  

1. a prefix meaning “through,” “thoroughly,” “utterly,” “very”: pervert; pervade; perfect.

2. Chemistry. a prefix used in the names of inorganic acids and their salts that possess the maximum amount of the element specified in the base word: percarbonic (H 2 C 2 O5 ), permanganic (HMnO4 ), persulfuric (H 2 S 2 O8 ), acids; potassium permanganate (KMnO4 ); potassium persulfate (K 2 S 2 O8 ).

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per. ³ American  

abbreviation

1. percentile.

2. period.

3. person.

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Per. ⁴ American  

abbreviation

1. Persia.

2. Persian.

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per- ¹ British  

prefix

1. through

   pervade

2. throughout

   perennial

3. away, beyond

   perfidy

4. completely, throughly

   perplex

5. (intensifier)

   perfervid

6. indicating that a chemical compound contains a high proportion of a specified element

   peroxide

   perchloride

7. indicating that a chemical element is in a higher than usual state of oxidation

   permanganate

   perchlorate

8. (not in technical usage) a variant of peroxy-

   persulphuric acid

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per ² British  

/ pə, pɜː /

determiner

1. for every

   three pence per pound

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preposition

1. (esp in some Latin phrases) by; through

2. according to

   as per specifications

3. informal as usual

PER ³ British  

abbreviation

1. Professional Employment Register

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Usage

Per meaning a or an or for each occurs chiefly in technical or statistical contexts: miles per gallon; work-hours per week; feet per second; gallons of beer per person per year. It is also common in sports commentary: He averaged 16 points per quarter. Per is sometimes criticized in business writing in the sense “according to” and is rare in literary writing.

Etymology

Origin of per¹

First recorded in 1580–90; from Latin: “through, by, for, for each”; for

Origin of per-²

From Latin, combining form of per, and used as an intensive; per

Example Sentences

Children also have higher respiratory rates than adults, as well as larger lung surface area relative to their body size, resulting in higher doses of pollution per breath.

From Los Angeles Times • Apr. 3, 2026

Some monitors there recorded levels of PM2.5 -- particles small enough to enter the bloodstream and linked to diseases like cancer -- of over 900 micrograms per cubic metre.

From Barron's • Apr. 3, 2026

Factoring in rent from the tenant, our out-of-pocket costs for the mortgage would be $4,000 per month.

From MarketWatch • Apr. 3, 2026

The proposal would cap the number of A’s per course at 20%, plus an additional four A’s to account for smaller courses with more variability.

From The Wall Street Journal • Apr. 3, 2026

Then we both looked away, per the unspoken terms of the Donut Truce.

From "Bye Forever, I Guess" by Jodi Meadows