Radiation

The act of radiating, or the state of being radiated; emission and diffusion of rays of light; beamy brightness.

The shooting forth of anything from a point or surface, like the diverging rays of light; as, the radiation of heat.

The emission of energy as electromagnetic waves or as moving subatomic particles

(medicine) the treatment of disease (especially cancer) by exposure to a radioactive substance

syndrome resulting from exposure to ionizing radiation (e.g., exposure to radioactive chemicals or to nuclear explosions); low doses cause diarrhea and nausea and vomiting and sometimes loss of hair; greater exposure can cause sterility and cataracts and some forms of cancer and other diseases; severe exposure can cause death within hours; "he was suffering from radiation"

energy that is radiated or transmitted in the form of rays or waves or particles

the spontaneous emission of a stream of particles or electromagnetic rays in nuclear decay

the act of spreading outward from a central source