In a state of rot or deterioration, breaking down naturally over time.
From Old French decayer, from Latin de- (down) + cadere (to fall). The meaning originally referred to something falling apart or falling into a lower state.
The Latin root 'cadere' meaning 'to fall' also gives us 'cascade' and 'accident'—all words about things falling, which is why decay is basically nature's way of making things fall apart slowly.
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