The Collaborative International Dictionary of English v.0.48:

Decay \De*cay"\, v. t.
   1. To cause to decay; to impair. [R.]
      [1913 Webster]

            Infirmity, that decays the wise.      --Shak.
      [1913 Webster]

   2. To destroy. [Obs.] --Shak.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Decay \De*cay"\, n.
   1. Gradual failure of health, strength, soundness,
      prosperity, or of any species of excellence or perfection;
      tendency toward dissolution or extinction; corruption;
      rottenness; decline; deterioration; as, the decay of the
      body; the decay of virtue; the decay of the Roman empire;
      a castle in decay.
      [1913 Webster]

            Perhaps my God, though he be far before,
            May turn, and take me by the hand, and more
            May strengthen my decays.             --Herbert.
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            His [Johnson's] failure was not to be ascribed to
            intellectual decay.                   --Macaulay.
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            Which has caused the decay of the consonants to
            follow somewhat different laws.       --James Byrne.
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   2. Destruction; death. [Obs.] --Spenser.
      [1913 Webster]

   3. Cause of decay. [R.]
      [1913 Webster]

            He that plots to be the only figure among ciphers,
            is the decay of the whole age.        --Bacon.

   Syn: Decline; consumption. See Decline.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Decay \De*cay"\, v. i. [imp. & p. p. Decayed; p. pr. & vb. n.
   Decaying.] [OF. decaeir, dechaer, decheoir, F. d['e]choir,
   to decline, fall, become less; L. de- + cadere to fall. See
   Chance.]
   To pass gradually from a sound, prosperous, or perfect state,
   to one of imperfection, adversity, or dissolution; to waste
   away; to decline; to fail; to become weak, corrupt, or
   disintegrated; to rot; to perish; as, a tree decays; fortunes
   decay; hopes decay.
   [1913 Webster]

         Ill fares the land, to hastening ills a prey,
         Where wealth accumulates and men decay.  --Goldsmith.
   [1913 Webster]

WordNet (r) 3.0 (2006):

decay
    n 1: the process of gradually becoming inferior
    2: a gradual decrease; as of stored charge or current [syn:
       decay, decline]
    3: the organic phenomenon of rotting [syn: decay,
       decomposition]
    4: an inferior state resulting from the process of decaying;
       "the corpse was in an advanced state of decay"; "the house
       had fallen into a serious state of decay and disrepair"
    5: the spontaneous disintegration of a radioactive substance
       along with the emission of ionizing radiation [syn: decay,
       radioactive decay, disintegration]
    v 1: lose a stored charge, magnetic flux, or current; "the
         particles disintegrated during the nuclear fission process"
         [syn: disintegrate, decay, decompose]
    2: fall into decay or ruin; "The unoccupied house started to
       decay" [syn: decay, crumble, dilapidate]
    3: undergo decay or decomposition; "The body started to decay
       and needed to be cremated"

The Free On-line Dictionary of Computing (19 January 2023):

decay

   [Nuclear physics] An automatic conversion which is applied to
   most array-valued expressions in C; they "decay into"
   pointer-valued expressions pointing to the array's first
   element.  This term is not used in the official standard for
   the language.

   [Jargon File]


The Jargon File (version 4.4.7, 29 Dec 2003):

decay
 n.,vi

    [from nuclear physics] An automatic conversion which is applied to most
    array-valued expressions in C; they ‘decay into’ pointer-valued
    expressions pointing to the array's first element. This term is borderline
    techspeak, but is not used in the official standard for the language.