(1):

(n.) One who, or that which, is left or taken in the place of another, as a child exchanged by fairies.

(2):

(n.) A simpleton; an idiot.

(3):

(n.) One apt to change; a waverer.

(4):

(a.) Taken or left in place of another; changed.

(5):

(a.) Given to change; inconstant.