sacra

/S AE1 K R AH0/
noun
  1. 1

    Sacral artery

noun
  1. 1

    A large triangular bone at the base of the spine, located between the two ilia (wings of the pelvis) and formed from vertebrae that fuse in adulthood.

Source: https://en.wiktionary.org/wiki/sacra, https://en.wiktionary.org/wiki/sacrum