Webster's Revised Unabridged Dictionary · 1913

Decay

Decay , intransitive verb

[Old French decaeir, dechaer, decheoir, French déchoir, to decline, fall, become less; Latin 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.
Ill fares the land, to hastening ills a prey, Where wealth accumulates and men decay. — Goldsmith

Decay , transitive verb

1.
To cause to decay; to impair. [Rare]
Infirmity, that decays the wise. — Shakespeare
2.
To destroy. [Obsolete] — Shakespeare

Decay , noun

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.
Perhaps my God, though he be far before, May turn, and take me by the hand, and more -- May strengthen my decays. — Herbert
His [Johnson's] failure was not to be ascribed to intellectual decay. — Macaulay
Which has caused the decay of the consonants to follow somewhat different laws. — James Byrne
2.
Destruction; death. [Obsolete] — Spenser
3.
Cause of decay. [Rare]
He that plots to be the only figure among ciphers, is the decay of the whole age. — Bacon