r
Save This Word!
Ecology.
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.
QUIZ
FIRE UP YOUR VOCAB FOR A "RED" SYNONYMS QUIZ
No fire engine reds here, only a fierce collection of vibrant words for the color red to test yourself on.
Question 1 of 7
What does "amaranth" mean?
Meet Grammar CoachImprove Your Writing
Also called Malthusian parameter .
Other definitions for r (2 of 10)
r
abbreviation
Other definitions for r (3 of 10)
R1
or r
[ ahr ]
/ ɑr /
noun, plural R's or Rs, r's or rs.
the 18th letter of the English alphabet, a consonant.
any spoken sound represented by the letter R or r, as in ran, carrot, or rhyme.
something having the shape of R.
a written or printed representation of the letter R or r.
a device, as a printer's type, for reproducing the letter R or r.
Other definitions for r (4 of 10)
R2
[ ahr ]
/ ɑr /
verb
Informal. are: Oysters R in season.
Other definitions for r (5 of 10)
R3
abbreviation
Trademark. restricted: a rating assigned to a movie by the Motion Picture Association of America indicating that children under the age of 17 will not be admitted to a theater showing the film unless accompanied by an adult.
Origin of R
3An American designation established in 1968
Other definitions for r (6 of 10)
R4
abbreviation
Other definitions for r (7 of 10)
R5
Symbol.
the 18th in order or in a series.
Biochemistry. arginine.
Physics. universal gas constant.
registered trademark: written as superscript ® following a name registered with the U.S. Patent and Trademark Office.
Other definitions for r (8 of 10)
r.
abbreviation
Other definitions for r (9 of 10)
R.1
or R.
abbreviation
(in prescriptions) take.
Origin of R.
1From the Latin word recipe
Other definitions for r (10 of 10)
R.2
abbreviation
Dictionary.com Unabridged
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2021
How to use r in a sentence
British Dictionary definitions for r (1 of 5)
r
R
/ (ɑː) /
noun plural r's, R's or Rs
the 18th letter and 14th consonant of the modern English alphabet
a speech sound represented by this letter, in English usually an alveolar semivowel, as in red
See three Rs
British Dictionary definitions for r (2 of 5)
R
symbol for
British Dictionary definitions for r (3 of 5)
r.
abbreviation for
rare
recto
Also: r rod (unit of length)
ruled
cricket baseball run(s)
British Dictionary definitions for r (4 of 5)
R.
r.
abbreviation for
registered (trademark)
right
river
rouble
British Dictionary definitions for r (5 of 5)
R.
abbreviation for
Word Origin for R.
(sense 3) Latin: Queen (sense 6) Latin: King
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Medical definitions for r (1 of 2)
r
abbr.
racemic
Medical definitions for r (2 of 2)
R
abbr.
right
radical (usually an alkyl or aryl group)
respiration
respiratory exchange ratio
or r roentgen
The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
Scientific definitions for r (1 of 2)
r
Abbreviation of radius
Scientific definitions for r (2 of 2)
R
The symbol for resistance.
The American Heritage® Science Dictionary
Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Other Idioms and Phrases with r
R
see three R's.
The American Heritage® Idioms Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.