What term is used for any body of flowing water confined within a channel, regardless of size?

The term used for any body of flowing water confined within a channel, regardless of size, is "stream." This definition encompasses various sizes of flowing water bodies, including larger rivers and smaller creeks. The key aspect is that a stream is essentially any flow of water that is contained within a defined bank or channel, allowing for consistent movement in one direction due to gravity.

While the other options refer to specific types or sizes of water bodies, "stream" is the most general term that accurately captures the essential characteristic of flowing water in a channel. Rivers are generally larger and more significant in their flow and impact, creeks are smaller tributaries that can be considered streams, and springs refer to sources of groundwater that emerge to the surface, rather than flowing through a channel. Therefore, the term "stream" is the most comprehensive and suitable for describing any flowing water confined within a channel.