adjective (a)

• capable of or tending to change in form or quality or nature(adj.all)

  Example:
  A mutable substance.
  The mutable ways of fortune.
  Mutable weather patterns.
  A mutable foreign policy.
  

  Synonym:
  changeable
  Antonym:
  changeless, immutable
  

  source: wordnet30
• Capable of alteration; subject to change; changeable in form, qualities, or nature.(adjective)

  source: webster1913