riv·er 
/ˈrɪvɚ/ noun
plural riv·ers /ˈrɪvɚ/ noun [count] 1 : a large natural flow of water that crosses an area of land and goes into an ocean, a lake, etc.
▪ the Mississippi River ▪ The raft is too small to use on this part of the river. ▪ They have a house on the river. [=on land next to the river] ▪ Large boats came up/down the river. [=in the opposite/same direction that the river is flowing] ▪ the mouth of the river = the river's mouth = the river mouth [=the place where the river enters the ocean] — see color picture; compare stream 2 : a large flow of something
▪ Rivers of mud flowed down the hillside. — often + of ▪ The jet stream is a river of air. ▪ I cried a river of tears. [=I cried a lot]
▪ the Mississippi River ▪ The raft is too small to use on this part of the river. ▪ They have a house on the river. [=on land next to the river] ▪ Large boats came up/down the river. [=in the opposite/same direction that the river is flowing] ▪ the mouth of the river = the river's mouth = the river mouth [=the place where the river enters the ocean] — see color picture; compare stream
▪ Rivers of mud flowed down the hillside. — often + of ▪ The jet stream is a river of air. ▪ I cried a river of tears. [=I cried a lot]
sell (someone) down the river — see 1sell
up the river
US, old-fashioned + informal : to prison
▪ They sent him up the river for 10 years.
▪ They sent him up the river for 10 years.
