the process by which organic matter rots or decomposes.
The apple showed signs of decay after being left out too long.
Bacteria cause tooth decay if you don't brush regularly.
✦ From Middle English 'decaye', from Old French 'decair', from Latin 'decadere' meaning 'to fall down or away', from 'de-' (down) + 'cadere' (to fall).
to rot or decompose gradually due to bacteria or fungi.
Food will decay if not stored properly.
The old books are decaying in the damp basement.
a gradual decline in health, strength, or quality.
Urban decay has affected many city centers.
The empire suffered from moral decay.
the spontaneous transformation of a radioactive substance into a different element by emission of radiation.
Radioactive decay releases energy.
The half-life measures the rate of decay.
