a basic unit of exposure to X-rays, gamma rays, or other ionizing radiation, equal to the amount of radiation that will produce an electric charge of 0.000258 coulomb per kilogram of dry air: abbrev. R
Origin of roentgenafter Roentgen
1845-1923; Ger. physicist: discoverer of X-rays
nounAbbr. R or r
A unit of radiation exposure equal to the quantity of ionizing radiation that will produce one electrostatic unit of electricity in one cubic centimeter of dry air at 0°C and standard atmospheric pressure.
Origin of roentgenAfter Wilhelm Conrad Roentgen.