- ilion (4th to 7th centuries)
ilium (plural ilia)
- (anatomy) The upper and widest of the three bones that make up each side of the hipbone and pelvis.
- (anatomy, obsolete) The ileum, part of the small intestine.
Note that in modern usage, ilium always refers to the bones of the hip and pelvis while ileum always refers to the part of the small intestine. To remember the different spellings, one rule is that there is an "i" in the middle of ilium and one in hip.