noun
radioactivity
The physical property of emitting radiation from atomic nuclei. Used in scientific and technical contexts.
この地域の放射能レベルは安全基準を下回っている。
The radioactivity level in this area is below the safety standard.
noun
Colloquial use referring to radiation itself, often in everyday conversation about contamination or exposure. Technically, 放射線 is the precise term for radiation rays.
See also: 放射線
放射能が漏れているかもしれない。
Radiation might be leaking.
noun
radioactive material
Colloquial extension referring to radioactive substances. In formal contexts, 放射性物質 is preferred.
See also: 放射性物質
事故で放射能が飛散した。
Radioactive material was scattered by the accident.