Definitions of diminished:

• adjective:   impaired by diminution
• adjective:   (of musical intervals) reduction by a semitone of any perfect or minor musical interval

  Example: "A diminished fifth"

• adjective:   made to seem smaller or less (especially in worth)
• adjective:   (of an organ or body part) diminished in size or strength as a result of disease or injury or lack of use