- In general, "degeneracy" means "reverting to an earlier, simpler, state"
- In mathematics, a limiting case in which a class of object changes its nature so as to belong to another, usually simpler, class. See mathematical degeneracy.
- In physics, the mathematical meaning applies, and also see degenerate matter.
- The term "moral degeneracy" is sometimes used, based on the concept of atavism.
- The Nazis described modernist art as "degenerate art".