Definition of radiation

• energy that is radiated or transmitted in the form of rays or waves or particles
• the act of spreading outward from a central source
• 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"