decay

n.

1. A progressive worsening

   decline, decomposition, collapse, degeneracy, downfall, decadence, depreciation, decrease, consumption, corruption, spoilage, spoiling, rotting, retrogradation, wasting away, retrogression, degeneration, gradual crumbling, disrepair, loss of health, loss of strength, weakening, senescence, deterioration, breakdown, failure, ruination, extinction, progressive decline, dilapidation, dissolution, disintegration, decrepitude, ruin, crumbling, waste, breakup, corrosion, impairment, discoloration, reduction, wear and tear, falling off, failing, pejority; see also sense 2.

   Antonyms improvement*, increase*, preservation. *

2. Decomposition

   disintegration, putrefaction, corruption, adulteration, rot, rottenness, breakup, spoilage, carrion, putrescence, putridity, decrepitude, mold, rust, corrosion, oxidation, dry rot, black rot, caries, spur, atrophy, emaciation, blight, marasmus, gangrene, mildew, biodegredation, deliquescence, ravages of time*, way of all flesh*; see also sense 1.

   Antonyms growth*, germination, freshness.

decay

v.

decay implies gradual, often natural, deterioration from a normal or sound condition his teeth have begun to decay; rot refers to the decay of organic, esp. vegetable, matter, caused by bacteria, fungi, etc. rotting apples; putrefy suggests the offensive, foul-smelling rotting of animal matter bodies putrefying in the fields; spoil is the common informal word for the decay of foods fish spoils quickly in summer; molder suggest a slow, progressive, crumbling decay old buildings molder away; disintegrate implies the breaking up of something into parts or fragments so that the wholeness of the original is destroyed the sunken ship gradually disintegrated; decompose suggests the breaking up or separation of something into its component elements a decomposing chemical compound: it is also a somewhat euphemistic substitute for rot and putrefy