A rib or ribs.
[Latin costa, a rib.]
Several adjectives describe the ribs plus another part of the body: costocervical, of ribs and neck; costoclavicular, of the ribs and the clavicle or shoulder blade; costosternal, of the ribs and the sternum or breast bone. The usual adjective relating to the ribs is costal. The adjective costive means constipated and is not a member of this set.