r

1 of 4

noun

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 4

abbreviation (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 4

abbreviation (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 4

certification mark

—used to certify that a movie 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

Examples of r in a Sentence

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

• r-color
• roll one's r's

Kids Definition

r

1 of 2 noun

ˈär

often capitalized

: the 18th letter of the English alphabet

R

2 of 2 certification mark

—used to certify that a motion picture is of such a nature that admission is restricted to persons over a specified age (as 17) unless accompanied by a parent or guardian

Medical Definition

r

1 of 3 abbreviation

roentgen

R

2 of 3 abbreviation

1

Reaumur

2

rough

—used in bacteriology

R

3 of 3 symbol

chemical group and especially an organic chemical group

thiols have the general formula RSH