Ilium

Ilium is a medical/anatomical term denoting the uppermost and largest part of the hip bone (os coxae). It forms the superior and anterior portion of the pelvis, and serves as the major point of muscle attachment. In anatomy discussions, ilium contrasts with the ischium and pubis, which together comprise the hip bone. The word is pronounced with emphasis on the first syllable: ˈɪliəm.