'River' originally meant 'riverbank' — from Latin 'ripa.' The same root gave us 'rival' and 'arrive.'
A large natural stream of water flowing in a channel to the sea, a lake, or another such stream.
From Old French 'riviere' (river, bank, shore), from Vulgar Latin *rīpāria (riverbank, from the bank), from Latin 'rīpa' (bank, shore), from PIE *h₁reyp- (to scratch, to tear — a riverbank being land torn away by water). The word originally meant 'riverbank' and was transferred to the water itself — we named the river after its edge, not its flow. The same PIE root gave Latin 'rīvālis' (one who uses the same stream), the origin of English