Which part of the vertebral column is referred to as the tailbone?

The tailbone is anatomically referred to as the coccyx. It is the terminal segment of the vertebral column and consists of a small triangular bone that is made up of three to five fused vertebrae. The coccyx serves as an attachment point for ligaments and muscles and plays a role in supporting the body in a seated position. Its name derives from the Greek word "kokkyx," which means "cuckoo," due to its shape resembling a bird's beak.

The lumbar, sacrum, and thoracic regions, while part of the vertebral column, are distinct from the coccyx in both location and function. The lumbar region comprises the lower back, the sacrum is a large triangular bone located above the coccyx, and the thoracic region is the upper and mid-back segment where the ribs attach. Each of these parts has unique roles in providing structure and support to the body but does not refer specifically to the tailbone.