radiation/͵redIˋeʃən; ˌreIdiˈeIʃ$n/n [U] 1 a form of energy that comes especially from NUCLEAR reactions, which in large amounts can harm or kill people 辐射﹔〔尤指〕核辐射: radiation sickness 放射病2 energy in the form of heat or light that is sent out as waves that you cannot see 辐射的热能[光能]: ultraviolet radiation from the sun 太阳发出的紫外线辐射