atrophy

(of a body part or tissue) waste away or degenerate due to disuse.

"His leg muscles began to atrophy."

(of a skill or institution) gradually decline in effectiveness or vigour.

"Without practice, language skills can atrophy."

The process or state of wasting away, especially of a body part.

"Disuse can lead to severe muscle atrophy."

A decline or state of ineffectiveness, especially in a social context.

"The atrophy of local services was concerning."