r
1 of 4noun
ˈär 
plural r's or rs ˈärz
often capitalized, often attributive
1
a
: the 18th letter of the English alphabet
b
: a graphic representation of this letter
c
: a speech counterpart of orthographic r
2
: a graphic device for reproducing the letter r
3
: one designated r especially as the 18th in order or class
4
: something shaped like the letter R
r
2 of 4abbreviation (1)
1
radius
2
rain
3
range
4
rare
5
real
6
recto
7
red
8
repeat
9
rerun
10
resistance
11
right
12
roentgen
13
rook
14
rough
15
run
R
3 of 4abbreviation (2)
1
rabbi
2
radial
3
radical —used especially of a monovalent hydrocarbon radical
4
Rankine
5
Reaumur
6
recipe
7
registered trademark —often enclosed in a circle
8
regular
9
Republican
10
river
11
R-value
R
4 of 4certification mark
—used to certify that a motion picture is of such a nature that admission is restricted to persons over a specified age (such as 17) unless accompanied by a parent or guardian compare g, nc-17, pg, pg-13
Example Sentences
Noun There are two r's in “tomorrow.” “River” begins and ends with r.
Word History
First Known Use
Noun
before the 12th century, in the meaning defined at sense 1a
Phrases Containing r
Kids Definition
r 1 of 4
noun
ˈär
plural r's or rs
ˈärz
often capitalized
: the 18th letter of the English alphabet
r.
2 of 4abbreviation
right
R
3 of 4abbreviation
regular
R.
4 of 4abbreviation
rabbi
Medical Definition
r 1 of 3
abbreviation
roentgen
R
2 of 3abbreviation
1
Reaumur
2
rough —used in bacteriology
R
3 of 3symbol
chemical group and especially an organic chemical group
thiols have the general formula RSH