What does "decay" mean?

Additional senses

1. 2.To destroy. [Obs.] Shak.
2. 3.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.
3. 4.Destruction; death. [Obs.] Spenser.
4. 5.Cause of decay. [R.] He that plots to be the only figure among ciphers, is the decay of the whole age. Bacon. See Decline.