What does R... stand for?

What does R... mean?

R	Angle of Reflection Academic & Science » Physics
R	Are Computing » Texting
R	combined hormonal vaginal ring Medical » Prescription
R	Ideal Gas Constant (8.314 joules per Kelvin) Academic & Science » Chemistry
R	Ohm Miscellaneous » Unit Measures
R	Rabbi Community » Synagogues
R	Rabbi Community » Religion
R	Rabbit Miscellaneous » Food
R	Rabid Miscellaneous » Dogs Related
R	Rabies Medical » Veterinary
R	Race Community » Sports
R	Racer Community » Sports
R	Racial Governmental » FBI Files
R	Racing Community » Sports
R	Racism Community
R	Rack Community » Sports
R	Radfahrabteilung (German Bicycle Battalion, World War II) Governmental » Military
R	Radial Governmental » Military
R	Radial Governmental » NASA
R	Radial Governmental » Transportation
R	Radial Miscellaneous
R	Radiancy Academic & Science » Chemistry
R	Radiancy Academic & Science » Meteorology
R	Radiancy Academic & Science » Ocean Science
R	Radians Miscellaneous » Unit Measures