Real Dictionary

innominate bone in American English
either of the two large, irregular bones that, together with the sacrum and coccyx, make up the pelvis: it is formed of three bones, the ilium, ischium, and pubis, which become fused in the adult
noun: either of the two bones forming the sides of the pelvis, each consisting of three consolidated bones, the ilium, ischium, and pubis

innominate bone in British English
noun: either of the two bones that form the sides of the pelvis, consisting of three fused components, the ilium, ischium, and pubis