ˈsakrəm, ˈsāk- noun
( plural sacra -rə)
Etymology: New Latin, from Late Latin (in os sacrum last bone of the spine, translation of Greek hieron osteon ), from Latin, neuter of sacer sacred
: the part of the vertebral column that is directly connected with or forms a part of the pelvis by articulation with the ilia, that consists of a single vertebra or of several more or less consolidated, that has in the transverse processes expanded ends fused into a solid bony mass on each side, and that in man forms the dorsal wall of the pelvis and consists of five united vertebrae diminishing in size to the apex which bears the coccyx — compare synsacrum