Source : Webster's Revised Unabridged Dictionary (1913)

Ilium \Il"i*um\, n. [See {Ileum}.] (Anat.)
   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}. [Written
   also {ilion}, and {ileum}.]

Source : WordNet®

Ilion
     n : an ancient city in Asia Minor that was the site of the
         Trojan War [syn: {Troy}, {Ilium}]