Or (Russian: Орь) is a river in Orenburg Oblast of Russia and Aktobe Province of Kazakhstan. It is a left tributary of the Ural River, and is 332 km long, with a drainage basin of 18 600 km². The river is formed by the confluence of the Shiyli and Terisbutak Rivers, which have their sources on the western slopes of the Mugodzhar Hills, and it joins the Ural River by the city of Orsk. Most of its discharge are from melting snow. The average discharge, 61 km from its mouth, is 21.3 m³/sek. The spring flooding lasts from April to mid-May. The rest of the year the waterlevel is very low. The river freezes in late October and is icebound until March - April. The river is used for irrigation and water supply.