sacrum /sāˈkrəm or sakˈrəm/ (anatomy)

A triangular bone composed of five fused vertebrae (sacral vertebrae) wedged between the two innominate bones, so as to form the keystone of the pelvic arch in humans

saˈcral adjective

sacralgia /-ralˈji-ə/ noun

Pain in the sacrum or region of the sacrum

sacralizaˈtion or sacralisaˈtion noun

Abnormal fusion of the sacrum with the fifth lumbar vertebra

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