ra·di·a·tion 
/ˌreɪdiˈeɪʃən/ noun
/ˌreɪdiˈeɪʃən/ noun [noncount] 1 : a type of dangerous and powerful energy that is produced by radioactive substances and nuclear reactions
▪ She was exposed to high levels of radiation. 2 medical : the use of controlled amounts of radiation for the treatment of diseases (such as cancer)
▪ He goes in for radiation next week. —called also radiation therapy, radiotherapy 3 a : energy that comes from a source in the form of waves or rays you cannot see
▪ ultraviolet radiation
b technical : the process of giving off energy in the form of waves or rays you cannot see
▪ the sun's radiation of heat
▪ She was exposed to high levels of radiation.
▪ He goes in for radiation next week. —called also radiation therapy, radiotherapy
▪ ultraviolet radiation
b technical : the process of giving off energy in the form of waves or rays you cannot see
▪ the sun's radiation of heat
