Replaceable and Mutable

adjective

• Capable of being replaced. .

• (a.) Capable of being replaced (by) or of being exchanged (for); as, the hydrogen of acids is replaceable by metals or by basic radicals.
• (a.) Capable or admitting of being put back into a place.
• (a.) Admitting of having its place supplied by a like thing or an equivalent; as, the lost book is replaceable.

adjective

• Capable of or tending to change in form or quality or nature.
  • usage: "a mutable substance"; "the mutable ways of fortune"; "mutable weather patterns"; "a mutable foreign policy"
  • synonyms: changeable

• (a.) Capable of alteration; subject to change; changeable in form, qualities or nature.
• (a.) Changeable; inconstant; unsettled; unstable; fickle.