What is the meaning of Decay?

The process or result of being gradually decomposed; rot, decomposition.

A deterioration of condition; loss of status, quality, strength, or fortune.

Overthrow, downfall, destruction, ruin.

The situation, in programming languages such as C, where an array loses its type and dimensions and is reduced to a pointer, for example by passing it to a function.

To deteriorate, to get worse, to lose strength or health, to decline in quality.

To undergo bit rot, that is, gradual degradation.

To undergo software rot, that is, to fail to be updated in a changing environment, so as to eventually become legacy or obsolete.

To undergo prolonged reduction in altitude (above the orbited body).

To rot, to go bad.

To change by undergoing fission, by emitting radiation, or by capturing or losing one or more electrons; to undergo radioactive decay.

To undergo optical decay, that is, to relax to a less excited state, usually by emitting a photon or phonon.

Loss of airspeed due to drag.

To cause to rot or deteriorate.

Of an array: to lose its type and dimensions and be reduced to a pointer, for example when passed to a function.

Source: wiktionary.org