The word degeneracy has more than one meaning:

• 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".