1. to decline in physical, mental, or moral qualities; deteriorate
  2. to diminish in quality; fall from a high or normal standard
  3. (of an organ or tissue) to lose structure or function
  4. (of a species or any of its traits or structures) to lose function or structural organization in the course of evolution, as the vestigial wings of a flightless bird


  1. having declined in physical or moral qualities; deteriorated; degraded
  2. having lost the qualities proper to the race or kind
  3. characterized by or associated with degeneracy
  4. (physics) A. (of modes of vibration of a system) having the same frequency, B. (of quantum states of a system) having equal energy


  1. a person who has declined, especially in morals, from a type considered standard
  2. a person or thing that reverts to an earlier stage of culture, development, or evolution
  3. a sexual deviate