Ilium n. : The dorsal one of the three principal bones comprising either lateral half of the pelvis; the dorsal or upper part of the hip bone. See Innominate bone, under Innominate.

Example:
How is Ilium, New York important to the plot or them of "Slaughterhouse-Five"?

Taxonomy
Ilium, bone, pelvis, body, biiliac width, hip bone, wing of ilium, Body of ilium, breadth, free encyclopedia, oss. ilii, external surface, acetabulum, measure, pelvic bone width, hip-joint, crest, internal surface.

Defination from the web:
Ilium. The ilium is the uppermost and largest bone of the pelvis, and appears in most vertebrates including mammals and birds, but not bony fish. ... The ilium of the human is divisible into two parts, the body and the ala; the separation is indicated on the top surface by a curved line, the ...