[1] : The Collaborative International Dictionary of English v.0.48

decay \decay"\, 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

[2] : The Collaborative International Dictionary of English v.0.48

decay \decay"\, 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.
      1913 webster

            his johnson's failure was not to be ascribed to
            intellectual decay.                   --macaulay.
      1913 webster

            which has caused the decay of the consonants to
            follow somewhat different laws.       --james byrne.
      1913 webster

   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
see also:
decline 

[3] : The Collaborative International Dictionary of English v.0.48

decay \decay"\, v. i. imp.  p. p. decayed; p. pr.  vb. n.
   decaying. of. decaeir, dechaer, decheoir, f. d'echoir,
   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
see also:
decayed decaying chance 

[4] : WordNet (r) 2.0

decay
     n 1: the process of gradually becoming inferior
     2: a gradual decrease; as of stored charge or current syn: decline
     3: the organic phenomenon of rotting syn: 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: radioactive
        decay, disintegration
     v 1: lose a stored charge, magnetic flux, or current; "the
          particles disintegrated during the nuclear fission
          process" syn: disintegrate, decompose
     2: fall into decay or ruin; "the unoccupied house started to
        decay" syn: crumble, delapidate
     3: undergo decay or decomposition; "the body started to decay
        and needed to be cremated"
see also:
decline decomposition radioactive decay disintegration disintegrate decompose 
crumble delapidate 

[5] : Moby Thesaurus II by Grady Ward, 1.0

154 moby thesaurus words for "decay":
   ablate, ablation, atomization, atomize, atrophy, biodegradability,
   biodegradation, break down, break up, breakup, canker, caries,
   carrion, catalysis, catalyst, collapse, come apart, consume,
   contaminate, corrode, corrosion, corrupt, corruption, crack up,
   crumble, crumble into dust, crumbling, curdle, dandruff,
   debilitate, decadence, decline, decompose, decomposition, decrease,
   defile, degenerate, degeneration, degradability, degradation,
   deteriorate, deterioration, dialysis, dilapidate, dilapidation,
   diminish, disintegrate, disintegration, disjoin, disjunction,
   disorganization, disorganize, dissociation, dissolution, dissolve,
   downfall, dry rot, dwindle, ebb, enfeeble, erode, erosion,
   excrement, fading, failing, fall into decay, fall to pieces,
   ferment, fester, filth, fission, foul matter, foulness, furfur,
   gangrene, go bad, go off, go to pieces, go to pot, go to seed,
   hydrolysis, hydrolyst, incoherence, mess, mildew, mold, molder,
   mortification, mortify, mould, moulder, muck, mucus, necrose,
   necrosis, obscenity, ordure, oxidation, oxidization, perish,
   photolysis, pollute, pus, putrefaction, putrefy, putresce,
   putrescence, putrid matter, putridity, putridness, rancidity,
   rancidness, rankle, rankness, ravages of time, resolution, rot,
   rottenness, rotting, ruin, rust, sap, scurf, scuz, slime, slough,
   smut, snot, sordes, sour, sphacelate, sphacelation, sphacelus,
   split, splitting, spoil, spoilage, suppurate, taint, thermolysis,
   tooth decay, turn, undermine, wane, waste away, wasting, weaken,
   weakening, wear, wear and tear, wear away, wither, work, wreck

[6] : Jargon File (4.3.1, 29 Jun 2001)

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.


see also:
c 

[7] : The Free On-line Dictionary of Computing (27 SEP 03)

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
     
     
see also:
c jargon file 

Decay >> D Words
Decay, definition of term: Decay
decay_pag1.html

Tooth Decay >> T Words
Tooth Decay, definition of term: Tooth Decay
tooth+decay_pag1.html