What is the meaning of alteration?

noun

• An event that occurs when something passes from one state or phase to another.
  • usage: "the change was intended to increase sales"; "this storm is certainly a change for the worse"; "the neighborhood had undergone few modifications since his last visit years ago"
  • synonyms: change, modification
• The act of making something different (as e. G. The size of a garment.
  • synonyms: modification, adjustment
• The act of revising or altering (involving reconsideration and modification. )
  • usage: "it would require a drastic revision of his opinion"
  • synonyms: revision