decay decay /dɪˈkeɪ/

noun

1. () A gradual decrease; as of stored charge or current  ( decline , decay )
   a gradual decrease; as of stored charge or current
     The decay of organic matter released a foul smell in the forest.
   The decay of organic matter released a foul smell in the forest.
   
2. () The process of gradually becoming inferior  ( decay )
   the process of gradually becoming inferior
   
3. () The organic phenomenon of rotting  ( decomposition , decay )
   the organic phenomenon of rotting
   
   
4. The spontaneous disintegration of a radioactive substance along with the emission of ionizing radiation  ( decay , disintegration , radioactive decay )
   the spontaneous disintegration of a radioactive substance along with the emission of ionizing radiation
   
5. An inferior state resulting from the process of decaying  ( decay )
   an inferior state resulting from the process of decaying
    The corpse was in an advanced state of decay
   the corpse was in an advanced state of decay
    The house had fallen into a serious state of decay and disrepair
   the house had fallen into a serious state of decay and disrepair
   

verb

1. () (physics) lose a stored charge, magnetic flux, or current  ( decompose , disintegrate , decay )
   (physics) lose a stored charge, magnetic flux, or current
    The particles disintegrated during the nuclear fission process
   the particles disintegrated during the nuclear fission process
   
2. () Fall into decay or ruin  ( crumble , dilapidate , decay )
   fall into decay or ruin
    The unoccupied house started to decay
   The unoccupied house started to decay
   
3. Undergo decay or decomposition  ( decay )
   undergo decay or decomposition
    The body started to decay and needed to be cremated
   The body started to decay and needed to be cremated