/ahr/
v. Informal. are: Oysters R in season.
1. Chem. radical.
2. Math. ratio.
3. regular: a man's suit or coat size.
4. Elect. resistance.
5. restricted: a rating assigned to a motion picture by the Motion Picture Association of America indicating that children under the age of 17 will not be admitted unless accompanied by an adult. Cf. G (def. 7), PG, PG-13, X . [abbrev. for RESTRICTED]
6. Theat. stage right.
7. Physics. roentgen.
8. Chess. rook.
Symbol.
1. the 18th in order or in a series, or, when I is omitted, the 17th.
2. ( sometimes l.c. ) the medieval Roman numeral for 80. Cf. Roman numerals .
3. Biochem. arginine.
4. Physics. See universal gas constant .
5. registered trademark: written as superscript ® following a name registered with the U.S. Patent and Trademark Office.