tributary

A tributary is a branch that flows into the main stream, like the White River, the Arkansas River, the Yazoo River and the Red River — each a tributary of the mighty Mississippi.

The noun tributary is related to the word tribute and both come from the Latin word tributum, meaning “a thing contributed or paid.” Long ago, a tributary was someone who was forced to pay a person or group in return for protection — namely from those who received the tribute. Today, a tributary is a smaller body of water that flows into a larger one or a contributing factor in something that happens