Yes, decays is a Scrabble word!

Verb

1. Lose a stored charge, magnetic flux, or current

2. Fall into decay or ruin

3. Undergo decay or decomposition

Noun

1. The process of gradually becoming inferior

2. A gradual decrease; as of stored charge or current

3. The organic phenomenon of rotting

4. An inferior state resulting from the process of decaying

5. The spontaneous disintegration of a radioactive substance along with the emission of ionizing radiation