What is the common name for the sacrum bone?

The sacrum is commonly referred to as the "sacral" region of the spine. This term encompasses the anatomical area associated with the sacrum, which is a large, triangular bone located at the base of the spine, connecting the lumbar vertebrae above it to the coccyx below. The sacrum is an important structure as it supports the weight of the upper body when standing and sitting and helps in the stability of the pelvis.

While terms like "coccyx" and "lower spine" relate to parts of the spine, they do not accurately represent the sacrum specifically. The coccyx, or tailbone, is actually situated beneath the sacrum, indicating that it is not synonymous. "Lower spine" is a broader term that can refer to various sections of the lumbar region as well as the sacrum but lacks the specificity needed to identify the sacrum uniquely. "Sacral vertebra" could imply the individual vertebrae that form the sacrum, but this term does not capture the common name of the bone itself. Thus, referring to the sacrum as "sacral" is the most accurate and widely recognized terminology.