ileumPronunciation: /ˈɪlɪəm/Definition of ileum noun (plural ilea /ɪlɪə/) Anatomy the third portion of the small intestine, between the jejunum and the caecum. Derivatives ileac adjective ileal adjective Origin: late 17th century: from medieval Latin, variant of iliumileum in other Oxford dictionaries Definition of ileum in the US English dictionary
