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• r
  r

  the theoretical intrinsic rate of increase of a population, equivalent to the difference between the birth and death rates divided by the number of individuals in the population.
• R
  R

  noun

  the 18th letter of the English alphabet, a consonant.
• r.
  r.

  abbreviation

  rabbi.
• R.
  R.

  abbreviation

  (in prescriptions) take.

r

¹ American  

Ecology.

1. the theoretical intrinsic rate of increase of a population, equivalent to the difference between the birth and death rates divided by the number of individuals in the population.

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r ² American  

abbreviation

rs plural

1. radius.

2. Commerce. registered.

3. Electricity. resistance.

4. Physics. roentgen.

5. royal.

6. ruble.

7. rupee.

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R ³ American  

[ahr] / ɑr /

Or r

noun

R's, plural Rs, plural r's, plural rs plural

1. the 18th letter of the English alphabet, a consonant.

2. any spoken sound represented by the letter R or r, as in ran, carrot, or rhyme.

3. something having the shape of R .

4. a written or printed representation of the letter R or r.

5. a device, as a printer's type, for reproducing the letter R or r.

6. three R's.

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R ⁴ American  

[ahr] / ɑr /

verb

1. Informal. are.

   Oysters R in season.

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R ⁵ American  

abbreviation

1. Trademark. restricted: a rating assigned to a movie by the MPA indicating that children under the age of 17 will not be admitted to a theater showing the film unless accompanied by an adult.

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R ⁶ American  

abbreviation

1. Chemistry. radical.

2. Mathematics. ratio.

3. regular: a man's suit or coat size.

4. Electricity. resistance.

5. Theater. stage right.

6. Physics. roentgen.

7. Chess. rook.

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R ⁷ American  

Symbol.

1. the 18th in order or in a series.

2. (sometimes lowercase) the medieval Roman numeral for 80.

3. Biochemistry. arginine.

4. Physics. universal gas constant.

5. registered trademark: written as superscript ® following a name registered with the U.S. Patent and Trademark Office.

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r. ⁸ American  

abbreviation

rs plural

1. rabbi.

2. railroad.

3. railway.

4. range.

5. rare.

6. Commerce. received.

7. recipe.

8. replacing.

9. residence.

10. right.

11. rises.

12. river.

13. road.

14. rod.

15. royal.

16. rubber.

17. ruble.

18. Baseball. run; runs.

19. rupee.

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R. ⁹ American  

Or R.

abbreviation

1. (in prescriptions) take.

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R. ¹⁰ American  

abbreviation

1. rabbi.

2. Radical.

3. radius.

4. railroad.

5. railway.

6. (in South Africa) rand; rands.

7. Réaumur.

8. rector.

9. redactor.

10. regina.

11. Republican.

12. response.

13. rex.

14. river.

15. road.

16. royal.

17. ruble.

18. rupee.

19. Theater. stage right.

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R. ¹ British  

abbreviation

1. registered (trademark)

2. right

3. river

4. rouble

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R. ² British  

abbreviation

1. rabbi

2. rector

3. Regina

4. Republican

5. response (in Christian liturgy)

6. Rex

7. River

8. Royal

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R ³ British  

symbol

1. chem radical

2. currency

   1. rand

   2. rupee

3. Réaumur temperature (scale)

4. physics electronics resistance

5. roentgen or röntgen

6. chess rook

7. Royal

8. chem gas constant

9. 1. restricted exhibition (used to describe a category of film certified as unsuitable for viewing by anyone under the age of 18)

   2. ( as modifier )

      an R film

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r. ⁴ British  

abbreviation

1. rare

2. recto

3. Also: r.  rod (unit of length)

4. ruled

5. cricket baseball run(s)

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r ⁵ British  

/ ɑː /

noun

1. the 18th letter and 14th consonant of the modern English alphabet

2. a speech sound represented by this letter, in English usually an alveolar semivowel, as in red

3. See three Rs

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r Scientific  

1. Abbreviation of radius

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R Idioms  

1. see three R's.

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Other Word Forms

Inflected Forms

noun

• Rs
  plural
• R's
  plural
• r's
  plural
• rs
  plural

Etymology

Origin of R⁵

An American designation established in 1968

Origin of R.⁹

From the Latin word recipe

Example Sentences

For Chicago, Sharon chose avery r. young, a Chicago-born Black poet, composer and activist.

From Washington Times • Apr. 28, 2021

As pitcher plants go, N. r. elongata is especially well suited to the bats.

From Science Magazine • Jan. 26, 2011

During 7 weeks of daily pitcher patrols, Grafe and his team found bats in more than one-quarter of the 223 N. r. elongata plants they checked.

From Science Magazine • Jan. 26, 2011

But after nine months, John's system started to react against his new kidney, and Dr. Dealy ordered an additional 200 r. of X rays.

From Time Magazine Archive

She erected a big white sign in the front yard on which she had carefully painted, in black letters with gold outlines, r. m. walls art studio.

From "The Glass Castle" by Jeannette Walls