The noun decay has 5 senses (first 3 from tagged texts)
1. (2) decay -- (the process of gradually becoming inferior)
2. (2) decay, decline -- (a gradual decrease; as of stored charge or current)
3. (1) decay, decomposition -- (the organic phenomenon of rotting)
4. decay -- (an inferior state resulting from the process of decaying; "the corpse was in an advanced state of decay"; "the house had fallen into a serious state of decay and disrepair")
5. decay, radioactive decay, disintegration -- (the spontaneous disintegration of a radioactive substance along with the emission of ionizing radiation)
Overview of verb decay
The verb decay has 3 senses (first 2 from tagged texts)
1. (3) disintegrate, decay, decompose -- (lose a stored charge, magnetic flux, or current; "the particles disintegrated during the nuclear fission process")
2. (2) decay, crumble, delapidate -- (fall into decay or ruin; "The unoccupied house started to decay")
3. decay -- (undergo decay or decomposition; "The body started to decay and needed to be cremated")