What does ileum mean?
The ileum is the last and longest segment of the small intestine. It begins where the jejunum ends and continues to the cecum, the pouch where the small intestine joins the large intestine. Although most chemical digestion occurs earlier, the ileum remains the major site for nutrient absorption, particularly for vitamin B12, bile salts, and many other nutrients. Its lining contains specialized structures that help complete absorption before undigested material passes into the large intestine. In medicine, the term appears in discussions of Crohn's disease, intestinal surgery, imaging, and reconstructive procedures involving the terminal ileum. The word is technical rather than everyday, but it is useful because it identifies a distinct portion of the digestive tract with its own important functions and characteristic medical conditions.
nounThe ileum is the final and longest section of the small intestine, extending from the jejunum to the cecum of the large intestine. It is the primary site for the absorption of most nutrients and vitamin B12.
- The final section of the small intestine, between the jejunum and the cecum.
"The ileum was partially removed during the operation, requiring the surgeon to reconnect the intestine."
"Damage to the ileum can prevent the body from absorbing vitamin B12 efficiently."
"An ileal conduit may be used to divert urine when the bladder requires removal."
The conventional anatomical plural is "ilea"; the form "ileums" is also encountered.
"The operation involved removing several inches of ileum."
The ileum is the small intestine's final act, ending where the large intestine begins.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does ileum come from?
The English word is a borrowing of the Latin anatomical term ileum. The deeper ancient derivation is disputed: reference works have connected it with Latin ilium, meaning "flank," and with Greek terms associated with twisting, possibly in reference to the intestine's position or convoluted form. It entered English as part of the established anatomical vocabulary of the digestive system.
Related word forms
How ileum is actually used
This is primarily a medical and anatomical term. In clinical writing, it is often used attributively, as in "ileal" or "ileal resection."
Easily confused with ileum
The ileum is part of the small intestine, whereas the ilium is the largest bone of the pelvis.
The jejunum is the middle section of the small intestine, while the ileum is its final section.