What is "ileon"

Ileum \Il"e*um\, n. [L. ile, ileum, ilium, pl. ilia, groin, flank.]

1. (Anat.) The last, and usually the longest, division of the small intestine; the part between the jejunum and large intestine. [Written also ileon, and ilium.]

2. (Anat.) See Ilium. [R.]

   Note: Most modern writers restrict ileum to the division of the intestine and ilium to the pelvic bone.