1. The ionizing electromagnetic radiation emitted from a highly evacuated tube, resulting from the excitation of the inner orbital electrons by the bombardment of the target anode with a stream of electrons from a heated cathode. Cf.: glass rays, under ray, indirect rays, under ray Syn: roentgen ray
2. Ionizing electromagnetic radiation produced by the excitation of the inner orbital electrons of an atom by other processes, such as nuclear delay and its sequelae. Syn: radiograph
