Skip to definition.
Get the FREE one-click dictionary software for Windows or the iPhone/iPad and Android apps


Noun: radiation  ,rey-dee'ey-shun
  1. Energy that is radiated or transmitted in the form of rays or waves or particles
     
  2. The act of spreading outward from a central source
     
  3. 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
    "he was suffering from radiation";
    - radiation sickness, radiation syndrome
     
  4. The spontaneous emission of a stream of particles or electromagnetic rays in nuclear decay
    - radioactivity
     
  5. The spread of a group of organisms into new habitats
     
  6. A radial arrangement of nerve fibers connecting different parts of the brain
     
  7. (medicine) the treatment of disease (especially cancer) by exposure to a radioactive substance
    "radiosensitive cancer cells can be treated with radiation";
    - radiotherapy, radiation therapy, actinotherapy, irradiation

Derived forms: radiations

Type of: action, activity, emanation, emission, energy, free energy, natural action, natural process, neural structure, spread, spreading, syndrome, therapy

Encyclopedia: Radiation, nuclear