R - Definition
r
n 1: a unit of radiation exposure; the dose of ionizing
radiation that will produce 1 electrostatic unit of
electricity in 1 cc of dry air [syn: roentgen, R]
2: (physics) the universal constant in the gas equation:
pressure times volume = R times temperature; equal to 8.3143
joules per kelvin per mole [syn: gas constant, universal
gas constant, R]
3: the 18th letter of the Roman alphabet [syn: R, r]
4: the length of a line segment between the center and
circumference of a circle or sphere [syn: radius, r]