ETYM French rivčre a river, Late Lat. riparia river, bank of a river, from Latin riparius belonging to a bank or shore, from ripa a bank or shore; of uncertain origin. Related to Arrive, Riparian.
A large natural stream of water (larger than a creek).
Long water course that flows down a slope along a channel. It originates at a point called its source, and enters a sea or lake at its mouth. Along its length it may be joined by smaller rivers called tributaries. A river and its tributaries are contained within a drainage basin.
One way of classifying rivers is their stage of development. A youthful stream is typified by a narrow V-shaped valley with numerous waterfalls, lakes, and rapids. When maturity is reached the river is said to be graded; erosion and deposition are delicately balanced as the river meanders across the extensive floodplain. At this stage the floodplain is characterized by extensive meanders, ox-bow lakes and levées.