coccyx

This term refers specifically to the anatomical structure commonly known as the tailbone. It is used primarily in medical, biological, and forensic contexts to describe the terminal end of the spinal column. While the term is technical, it is frequently used in clinical reports to describe injuries resulting from impact trauma.

As a singular anatomical entity, the word is treated as a countable noun, though it is most often encountered in the singular form when referring to a specific patient's anatomy. In comparative anatomy or pathology studies involving multiple specimens, the plural form is employed.