The coccyx (pronounce kok-siks) (Latin: os coccygis), commonly referred to as the tailbone, is the final segment of the human vertebral column. Comprised of three to five separate or fused vertebrae (the coccygeal vertebrae), below the sacrum, it is attached to the sacrum by a fibrocartilaginous joint, which permits limited movement between the sacrum and the coccyx. The term coccyx comes originally from the Greek language and means "cuckoo," referring to the shape of a cuckoo's beak.