R-2
— Noun
– English
~ street names for flunitrazepan
R
— Noun
– English
~ (physics) the universal constant in the gas equation: pressure times volume = R times temperature; equal to 8.3143 joules per kelvin per mole
R and B
— Noun
– English
~ a combination of blues and jazz that was developed in the United States by Black musicians; an important precursor of rock 'n' roll