Meaning of R in English

R

n.

Function: 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 ― compare G , NC-17 , PG , PG-13

Merriam Webster Collegiate English Dictionary.      Merriam Webster - Энциклопедический словарь английского языка.