What does ilium mean?
The ilium is the broad, upper portion of the hip bone and one of the three bones that form the adult os coxae. It supports much of the weight of the upper body and provides attachment points for muscles that move the thigh and stabilize the pelvis. Because it is part of the fused hip bone, the ilium is also called the upper hip bone or, less commonly, the haunch bone. In medical contexts, it is frequently mentioned in connection with pelvic and acetabular fractures. The word is specialized and is not generally used for the entire hip or pelvis. Although ilium and ileum have similar spellings and pronunciations, they refer to entirely different anatomical structures: the ilium is a bone, while the ileum is part of the small intestine. Its Latin name reflects its long-established role as the upper part of the hip.
nounThe large, flaring bone that forms the upper part of each hip bone and contributes to the pelvic girdle. In anatomy, it is one of the three bones that fuse to form the adult hip bone.
- The large bone forming the upper portion of the hip bone and contributing to the pelvic girdle.
"The X-ray revealed a fracture of the left ilium."
"The patient suffered a serious fracture of the left ilium."
"Anatomists study how the ilium connects with the other bones of the pelvis."
The standard anatomical plural is ilia, referring to the ilium bones on both sides of the body.
"The scan showed abnormalities in both ilia."
The ilium is the pelvis’s broad, wing-shaped anchor—and its name is easily mistaken for the ileum, a section of the small intestine.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does ilium come from?
The word comes through Latin, where ilium referred to the upper part of the hip or the flank. It is associated with the Greek word ilion, also meaning “flank.” In anatomical usage, ilium became established as the name for the large upper section of the hip bone, and related terms such as iliac and ilio- derive from this Latin base.
Related word forms
How ilium is actually used
A technical anatomical term used primarily in medicine, anatomy, radiology, and comparative anatomy. It is more specific than the general term “hip bone,” which can refer to the complete fused bone.
Easily confused with ilium
The ilium is a bone of the pelvis, whereas the ileum is the final section of the small intestine.