decay

Physics. (of a radioactive nucleus) to change spontaneously into one or more different nuclei in a process in which atomic particles, as alpha particles, are emitted from the nucleus, electrons are captured or lost, or fission takes place.

verb (used with object)

4.

to cause to decay or decompose; rot:

The dampness of the climate decayed the books.

noun

5.

decomposition; rot:

Decay made the wood unsuitable for use.

6.

a gradual falling into an inferior condition; progressive decline:

the decay of international relations; the decay of the Aztec civilizations.

7.

decline in or loss of strength, health, intellect, etc.:

His mental decay is distressing.

8.

Also called disintegration, radioactive decay. Physics. a radioactive process in which a nucleus undergoes spontaneous transformation into one or more different nuclei and simultaneously emits radiation, loses electrons, or undergoes fission.

9.

Aerospace. the progressive, accelerating reduction in orbital parameters, particularly apogee and perigee, of a spacecraft due to atmospheric drag.

1. degenerate, wither; putrefy. Decay,decompose,disintegrate,rot imply a deterioration or falling away from a sound condition. Decay implies either entire or partial deterioration by progressive natural changes: Teeth decay.Decompose suggests the reducing of a substance to its component elements: Moisture makes some chemical compounds decompose.Disintegrate emphasizes the breaking up, going to pieces, or wearing away of anything, so that its original wholeness is impaired: Rocks disintegrate.Rot is a stronger word than decay and is especially applied to decaying vegetable matter, which may or may not emit offensive odors: Potatoes rot.5. putrefaction. 7. deterioration, decadence, impairment, dilapidation, degeneration.

The breaking down or rotting of organic matter through the action of bacteria, fungi, or other organisms; decomposition.

The spontaneous transformation of a relatively unstable particle into a set of new particles. For example, a pion decays spontaneously into a muon and an antineutrino. The decay of heavy or unstable atomic nuclei (such as uranium or carbon-10) into more stable nuclei and emitted particles is called radioactive decay. The study of particle decay is fundamental to subatomic physics. See more at fundamental force, radioactive decay.