degeneration
/dɪˌdʒenəˈreɪʃən/noun
mass noun
1- the state or process of being or becoming degenerate; decline or deterioration退化过程（或状态）; 恶化; 堕落：
overgrazing has caused serious degeneration of grassland.
过度放牧已经导致了草地严重退化。
1.1
- Medicine deterioration and loss of function in the cells of a tissue or organ【医】恶化, 变性：
degeneration of the muscle fibres.
肌肉组织变性。