Meaning of RADIATION in English

RADIATION

[noun] [U] - heat, light, or elementary particles (= the most simple parts of matter) produced by an objectmicrowave/ultraviolet/electromagnetic radiationWith nuclear power, there is always the fear that there will be an escape of harmful radiation.Many servicemen suffered radiation sickness after being present without protection at the early atomic tests.

Cambridge English vocab.      Кембриджский английский словарь.