'sacrum' originates from Latin, specifically the word 'sacrum' (neuter of 'sacer'), where 'sacer' meant 'sacred' or 'holy'.

'sacrum' passed into English from Medieval or New Latin, where it was used both in religious contexts and later in anatomical writing to denote the bone at the base of the spine; the anatomical sense became standard in modern English.

Initially it meant 'a sacred thing' or 'something holy', but over time the term came to be used specifically for the anatomical bone now called the 'sacrum'.