Oxford Dictionary English gamma radiation nounnoun BrE BrE//ˌɡæmə reɪdiˈeɪʃn// ; NAmE NAmE//ˌɡæmə reɪdiˈeɪʃn// [uncountable] (also gamma rays [plural]) (physics) Energy and physical forces Add to my wordlistjump to other results high-energy rays of very short wavelength sent out by some radioactive substances See related entries: Energy and physical forcesSee gamma radiation in the Oxford Advanced American DictionaryCheck pronunciation: gamma radiation oxfordlearnersdictionaries.com