Ileus (/ˈɪliəs/; from Greek εἰλεός eileós, "intestinal obstruction") is a disruption of the normal propulsive ability of the gastrointestinal tract. Although ileus originally referred to any lack of digestive propulsion, including any bowel obstruction, up-to-date medical usage restricts its meaning to those disruptions caused by the failure of peristalsis, rather than by mechanical obstruction.