1. [ noun ] (physics) a unit of radiation exposure; the dose of ionizing radiation that will produce 1 electrostatic unit of electricity in 1 cc of dry air
Synonyms: roentgen
Related terms: radioactivity_unit
2. [ noun ] the 18th letter of the Roman alphabet
Related terms: letter Roman_alphabet
3. [ noun ] (physics) the universal constant in the gas equation: pressure times volume = R times temperature; equal to 8.3143 joules per kelvin per mole
Synonyms: universal_gas_constant gas_constant
Related terms: constant physics
4. [ noun ] (geometry) the length of a line segment between the center and circumference of a circle or sphere
Synonyms: radius
Related terms: length radius_of_curvature semidiameter diameter
Similar spelling:   Rh