Röntgen ray. (Physics)
Any of the rays produced when cathode rays strike upon surface of a solid (as the wall of the vacuum tube). Röntgen rays are noted for their penetration of many opaque substances, as wood and flesh, their action on photographic plates, and their fluorescent effects. They were called X rays by their discoverer, W. K. Röntgen. They also ionize gases, but cannot be reflected, or polarized, or deflected by a magnetic field. They are regarded as nonperiodic, transverse pulses in the ether. They are used in examining opaque objects, as for locating fractures or bullets in the human body.
© Webster 1913