ischium

The lowest of the three major bones that constitute each half of the pelvis.

In anatomy, the posterior part of the pelvic arch in vertebrates, the lowermost of the three parts forming the os innominatum.

In Crustacea, the third joint of the normally 7-jointed leg; the ischiopodite.

The lowest of the three bones that make up each side of the pelvis.

one of the three sections of the hipbone; situated below the ilium