Definitions:

1. A large, triangular bone formed by the fusion of five sacral vertebrae located between the lumbar spine and coccyx, and articulating with the pelvis. NOUN
   • The sacrum provides stability and support to the spine and pelvis.
2. A triangular bone at the base of the spine, situated between the two hip bones and froming the back part of the pelvis. NOUN
   • Lower back pain can sometimes originate near the sacrum.
3. That part of the vertebral column which is directly conncected with, or forms part of, the pelvis. NOUN
   • The X-ray showed a hairline fracture in the sacrum.