river (n.) Look up river at Dictionary.com
c.1300, from Old French riviere, from Vulgar Latin *riparia "riverbank, seashore, river" (cf. Spanish ribera, Italian riviera), noun use of fem. of Latin riparius "of a riverbank" (see riparian). The Old English word was ea "river," cognate with Gothic ahwa, Latin aqua (see aqua-).

U.S. slang phrase up the river "in prison" (1891) is originally in reference to Sing Sing prison, which was literally "up the (Hudson) river" from New York City. Phrase down the river "done with" perhaps echoes sense in to sell down the river (1851), originally of troublesome slaves, to sell from the Upper South to the harsher cotton plantations of the Deep South.