degeneration

noun4

1. •
   The process or state of growing worse, or the state of having become worse.

   • The modern cry of "more liberty and less creed" is a degeneration from a vertebrate to a jellyfish. — 1913
2. •
   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.
3. •
   Gradual deterioration, from natural causes, of any class of animals or plants or any particular organ or organs; hereditary degradation of type.
4. •
   A thing that has degenerated.