The fork-shaped bone from a turkey that is broken for good luck is called the wishbone.
Anatomically, the wishbone is the furcula, a structure formed by the fusion of a bird’s two clavicles. It connects the shoulders and helps support the chest during flight. In flying birds, the furcula can flex like a spring as the wings beat.
The custom of pulling the bone to determine who gets a wish is much older than Thanksgiving. Goose-bone divination was recorded in Europe by 1455, while the two-person wish-pulling tradition developed by the early 1600s. The English name “wishbone” is recorded from 1860.
A common mix-up is calling it the breastbone or keel bone. Those are different parts of a bird’s skeleton: the keel is a ridge on the sternum, while the wishbone lies higher in the chest between the shoulders. “Furcula” is the scientific term; “wishbone” is the familiar name used in the tradition.