The furcula ("little fork" in Latin) is a forked bone found in birds and theropod dinosaurs, formed by the fusion of the two clavicles. In birds, its function is the strengthening of the thoracic skeleton to withstand the rigors of flight.
The furcula is commonly referred to as a wishbone or merrythought because of the tradition that when two people hold the two sides of the bone and pull it apart, the one who gets the larger part will have a wish granted. Today the wishbone, once removed from the turkey or chicken, is first dried and then held between the little fingers of two opposing "wishers". Once the wish has been made the bone is pulled by each person. The wisher who breaks off a larger section of bone is assumed to have their wishes granted. Because this is commonly a Thanksgiving tradition, this bone is also called the Thanksgiving bone.
In the Southern United States, it is also referred to as pulley bone, especially when served as a piece of chicken with meat from both adjacent breasts attached.