Changeling. It was at one time a common belief that infants were sometimes taken from their cradles by fairies, who left instead their own weakly and starving elves. The children so left were called changelings, and were marked by their peevishness, and their backwardness in learning to walk and speak. As it was supposed that the fairies had no power to change children who had been christened, infants were carefully watched until such time as that ceremony had been performed.
This superstition is alluded to by Shakespeare, Spenser, and other poets, and is an essential part of the doctrine of fairy-lore almost everywhere. See Sikes's British Goblins (1879).