Longman Dictionary of Contemporary English - river

~ n 1 a natural and continuous flow of water in a long line across a country into the sea  (the Mississippi River | We swam to a large rock in the middle of the river. | river bank (=the land at the side of a river))  (We ate our lunch on the river bank. | mouth of the river (=where a river joins the sea) | up river (=in the opposite direction from the way the river is flowing))  (a ship sailing up river | down river (=in the same direction as the way the river is flowing)) 2 a large amount of moving liquid + of  (a river of hot lava flowing from the volcano)  (- see also sell sb down the river sell1 (12))