Merriam-Webster Collegiate Dictionary - degeneration

 noun  Date: 15th century  1. degenerate condition  2. a lowering of effective power, vitality, or essential quality to an enfeebled and worsened kind or state  3. intellectual, moral, or artistic decline  4.  a. progressive deterioration of physical characters from a level representing the norm of earlier generations or forms  b. deterioration of a tissue or an organ in which its function is diminished or its structure is impaired  Synonyms: see deterioration