sacrum

Meaning

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.

Synonyms

sacral bone

buttocks

lower back

rump

unusual physique

outstanding appearance

philosophic turn of mind

male organ

backbone

tail base

Etymology

From Latin os sacrum (“holy bone”), a calque of Ancient Greek ἱερὸν ὀστέον (hieròn ostéon). Apparently so called either because the sacrum was the part of the animal offered in sacrifice or because of a putative belief that it is where a person's soul resides. A third explanation is that the term is a translation of Ancient Greek ἱερόν (hierón), which has two meanings: “holy, sacred”, and “big” — big being a more appropriate description of the sacrum — but compare.