noun
(ecology, medicine) The process or result of being gradually decomposed; rot, decomposition.
A deterioration of condition; loss of status, quality, strength, or fortune.
(obsolete) Overthrow, downfall, destruction, ruin.
(programming) 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.
verb
(intransitive) To deteriorate, to get worse, to lose strength or health, to decline in quality.
(intransitive, of organic material) To rot, to go bad.
(intransitive, transitive, physics, chemistry, of an unstable atom) To change by undergoing fission, by emitting radiation, or by capturing or losing one or more electrons; to undergo radioactive decay.
(intransitive, transitive, physics, of a quantum system) To undergo optical decay, that is, to relax to a less excited state, usually by emitting a photon or phonon.
(intransitive, aviation) Loss of airspeed due to drag.
(transitive) To cause to rot or deteriorate.
(programming, intransitive) Of an array: to lose its type and dimensions and be reduced to a pointer, for example when passed to a function.