The Collaborative International Dictionary of English v.0.48:

Degeneration \De*gen`er*a"tion\, n. [Cf. F.
   d['e]g['e]n['e]ration.]
   1. The act or state of growing worse, or the state of having
      become worse; decline; degradation; debasement;
      degeneracy; deterioration.
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            Our degeneration and apostasy.        --Bates.
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   2. (Physiol.) That condition of a tissue or an organ in which
      its vitality has become either diminished or perverted; a
      substitution of a lower for a higher form of structure;
      as, fatty degeneration of the liver.
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   3. (Biol.) A gradual deterioration, from natural causes, of
      any class of animals or plants or any particular organ or
      organs; hereditary degradation of type.
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   4. The thing degenerated. [R.]
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            Cockle, aracus, . . . and other degenerations. --Sir
                                                  T. Browne.
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   Amyloid degeneration, Caseous degeneration, etc. See
      under Amyloid, Caseous, etc.
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WordNet (r) 3.0 (2006):

degeneration
    n 1: the process of declining from a higher to a lower level of
         effective power or vitality or essential quality [syn:
         degeneration, devolution] [ant: development,
         evolution]
    2: the state of being degenerate in mental or moral qualities
       [syn: degeneracy, degeneration, decadence, decadency]
    3: passing from a more complex to a simpler biological form
       [syn: degeneration, retrogression]