n. 1 a copious natural stream of water flowing in a channel to the sea or a lake etc. 2 a copious flow (a river of lava; rivers of blood). 3 (attrib.) (in the names of animals, plants, etc.) living in or associated with the river. river blindness a tropical disease of the skin caused by a parasitic worm, the larvae of which can migrate into the eye and cause blindness. river capture the diversion of the upper headwaters of a mountain stream into a more powerful one. sell down the river colloq. betray or let down. rivered adj. (also in comb.). riverless adj.
[ ME f. AF river, rivere, OF riviere river or river-bank ult. f. L riparius f. ripa bank ]