B2 noun ˌreɪ.di.oʊ.ækˈtɪv.ə.ti
radioactivity
放射性
Meaning
The emission of ionizing radiation or particles caused by the spontaneous disintegration of atomic nuclei.
Example
Radioactivity is used in medical treatments like cancer therapy.
放射性は、がん治療のような医療に用いられている。