ra·di·a·tion/ˏredɪ`eʃən; ˌreɪdiˈeɪʃən/ n [U] 1 a form of energy that comes from a nuclear reaction, that can be extremely harmful to living things （核）辐射〔核反应产生的能源形式，对生物极为危险〕: The level of radiation in the area is worrying. 这个地区的辐射强度令人担忧。 radiation sickness 放射病 2 energy in the form of heat or light sent out as beams that you cannot see 〔热或光的能量〕辐射: ultraviolet radiation from the sun 太阳发出的紫外线辐射