decay

decay [dē kā′, dikā′]

vi.

[ME decaien < Anglo-Fr & OFr decäir < VL * decadere: see DECADENCE]

1. to lose strength, soundness, health, beauty, prosperity, etc. gradually; waste away; deteriorate

2. to rot or decompose

3. to undergo radioactive disintegration spontaneously

vt.

to cause to decay

n.

1. a gradual decline; deterioration

2. a wasting away

3. a rotting or decomposing, as of vegetable matter

4.

a) rottenness

b) decayed or rotted matter

5.

a) the spontaneous disintegration of radioactive atoms with a resulting decrease in their number: see HALF-LIFE

b) the spontaneous disintegration of a particle or nucleus, as a meson, baryon, etc., as it changes into a more stable state: see RADIOACTIVE SERIES

SYN.- 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 disintegration of rocks ]; 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