noun (n)

• energy that is radiated or transmitted in the form of rays or waves or particles(noun.phenomenon)

  source: wordnet30
• the act of spreading outward from a central source(noun.act)

  source: wordnet30
• 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(noun.state)

  Example:
  He was suffering from radiation.
  

  Synonym:
  radiation sickness, radiation syndrome
  

  source: wordnet30
• the spontaneous emission of a stream of particles or electromagnetic rays in nuclear decay(noun.process)

  Synonym:
  radioactivity
  

  source: wordnet30
• the spread of a group of organisms into new habitats(noun.event)

  source: wordnet30
• a radial arrangement of nerve fibers connecting different parts of the brain(noun.body)

  source: wordnet30
• (medicine) the treatment of disease (especially cancer) by exposure to a radioactive substance(noun.act)

  Synonym:
  actinotherapy, irradiation, radiation therapy, radiotherapy
  

  source: wordnet30
• The act of radiating, or the state of being radiated; emission and diffusion of rays of light; beamy brightness.(noun)

  source: webster1913