The Open Dictionary

decay

noun

UK/dɪˈkeɪ/
US/dɪˈkeɪ/

Definitions of decay noun

  1. C2Uncountable

    the process of gradually deteriorating or declining in condition or quality.

    • environmental degradation/industrial decline/moral degradation/urban decline

    • dental caries

    • The structures had started to suffer from decay.

  2. Uncountablephysicsspecialized

    the process by which a radioactive substance transforms into a different form, emitting radiation in the process.

    • Radon is released during the natural decay of radioactive materials found in rocks and soil.

    • the rate of decay of beryllium-7

    • The decay of this substance releases energy.

verb

UK/dɪˈkeɪ/
US/dɪˈkeɪ/

Definitions of decay verb

  1. B2TransitiveIntransitive

    to gradually deteriorate, worsen, or diminish; to cause something to undergo this process.

    • Sugar can cause your teeth to decay.

    • The influence of the extended family has been waning for some time.

    • The stone carvings on the cathedral's facade have been corroded by pollution.

  2. Intransitivephysicsspecialized

    When a radioactive substance decays, it transforms into a different form, emitting radiation.

    • Radioactive uranium decays into stable lead at a predictable rate.

    • As actinium-225 decays, it emits short-lived, high-energy alpha particles.

    • Radiation is emitted when radioactive materials decay.