radiation (Noun) — Energy that is radiated or transmitted in the form of rays or waves or particles.
radiation (Noun) — The act of spreading outward from a central source.
radiation (Noun) — Syndrome resulting from exposure to ionizing radiation (e.g., exposure to radioactive chemicals or to nuclear explosions); low doses cause diarrhoea 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. ex. "he was suffering from radiation"
radiation (Noun) — The spontaneous emission of a stream of particles or electromagnetic rays in nuclear decay.
radiation (Noun) — The spread of a group of organisms into new habitats.
radiation (Noun) — A radial arrangement of nerve fibers connecting different parts of the brain.
radiation (Noun) — (medicine) the treatment of disease (especially cancer) by exposure to a radioactive substance. ex. "radiosensitive cancer cells can be treated with radiation"