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

Definition categories: phenomenon, energy

2. the act of spreading outward from a central source

Definition categories: act, emanation, emission

3. 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

Definition categories: state, syndrome

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

Similar word(s): radioactivity

Definition categories: process, emission

5. the spread of a group of organisms into new habitats

Definition categories: event, spread, spreading, action, activity

6. a radial arrangement of nerve fibers connecting different parts of the brain

Definition categories: body

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

Similar word(s): actinotherapy, irradiation, radiotherapy

Definition categories: act, therapy