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English definition of “half-life”

half-life

noun [C]     /ˈhɑːf.laɪf/ US  /ˈhæf-/ specialized
the length of time needed for the radioactivity of a radioactive substance to be reduced by halfRadiation and radioactivity
(Definition of half-life noun from the Cambridge Advanced Learner's Dictionary & Thesaurus © Cambridge University Press)
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