1. rotting or decomposing
2. gradually declining or deteriorating

1. present participle of decay: rotting or decomposing

Examples

• The decaying leaves created a rich compost for the garden.
• We could smell the decaying fish from across the pond.
• The decaying building was finally torn down last month.
• The old neighborhood showed signs of decaying infrastructure.
• Bacteria are decaying the organic matter in the soil.
• The wooden fence is slowly decaying from years of rain.
• Scientists studied the decaying radioactive material in the lab.