Jump to:

• per
  per

  preposition

  for each; for every.
• per-
  per-

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

  abbreviation

  percentile.
• Per.
  Per.

  abbreviation

  Persia.
• PER
  PER

  abbreviation

  Professional Employment Register

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.

---

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 ).

---

per. ³ American  

abbreviation

1. percentile.

2. period.

3. person.

---

Per. ⁴ American  

abbreviation

1. Persia.

2. Persian.

---

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

---

per ² British  

/ pə, pɜː /

determiner

1. for every

   three pence per pound

---

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

---

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”; see for

Origin of per-²

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

Example Sentences

The analysis also found that 64 percent of samples contained at least one per- and polyfluoroalkyl substance, also known as "forever chemicals", which are found throughout the environment and everyday products.

From Barron's • Jan. 29, 2026

In addition to pesticides, there’s been growing concerns about PFAS, short for per- and poly-fluoroalkyl substances.

From Salon • May 4, 2024

Man-made per- and polyfluoroalkyl substances, known as PFAS, are found in all sorts of industrial and consumer products, including carpets, rain jackets, and makeup.

From Slate • Apr. 18, 2024

They’re PFAS: a class of man-made chemicals called per- and polyfluoroalkyl substances.

From New York Times • Apr. 8, 2024

Averse implies reluc- tance or unwillingness, and usually characterizes a per- son.

From "Woe Is I" by Patricia T. O'Conner