The Collaborative International Dictionary of English v.0.48:

Ileus \Il"e*us\, n. [NL., fr. Gr. ?, ?, fr. ? to roll up.]
   (Med.)
   A morbid condition due to intestinal obstruction. It is
   characterized by complete constipation, with griping pains in
   the abdomen, which is greatly distended, and in the later
   stages by vomiting of fecal matter. Called also ileac
   passion or iliac passion.
   [1913 Webster]

WordNet (r) 3.0 (2006):

ileus
    n 1: blockage of the intestine (especially the ileum) that
         prevents the contents of the intestine from passing to the
         lower bowel [syn: intestinal obstruction, ileus]