Desuetude (noun)

1. The state or condition of disuse; disuse or cessation of use.
2. The state of being out of use or no longer practiced.

Origin:

From the latin "desuetudo" meaning "disuse".

Examples:

1. The law fell into desuetude after it was deemed unconstitutional.
2. The bridge fell into desuetude after a newer bridge was built.
3. The custom fell into desuetude after the war and never regained popularity.
4. The tradition fell into desuetude after the younger generations stopped practicing it.
5. The language fell into desuetude after it stopped being spoken by the last speaker.