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In general, "degeneracy" means "reverting to an earlier, simpler, state"

The term "moral degeneracy" is sometimes used by speakers commenting on the morality (or lack thereof) of a society: this usage has its roots in the concept of atavism.

Modernist art is sometimes described as "degenerate art".

In biology, see devolution.

In neuroscience, "degenerated" neurons means diseased or dying neuron.

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, these meanings apply:

The mathematical meaning.

Degenerate matter is a very highly compressed phase of matter where all or some of the electron orbits have collapsed from pressure.

Degenerate energy levels are different arrangements of the system which have the same energy.

Degenerate (humans), inferior human