Changeling

Webster's Dictionary of the English Language

·adj Given to change; inconstant.

II. Changeling ·noun One apt to change; a waverer.

III. Changeling ·adj Taken or left in place of another; changed.

IV. Changeling ·noun A simpleton; an Idiot.

V. Changeling ·noun One who, or that which, is left or taken in the place of another, as a child exchanged by fairies.