Definitions
1.nounIn pre-modern European mythology, an infant that was secretly exchanged for a mother's own baby by an evil creature. (In British, Irish and Scandinavian mythology the exchanged infants were thought to be those of fairies, sprites or trolls; in other places, they were ascribed to witches, devils, or demons.)
2.nounAn infant secretly exchanged with another infant by mistake or by human doing; swapling.
3.nounAn organism which can change shape to mimic others.
4.nounA simpleton; an idiot.
5.nounOne apt to change; a waverer.