A stream is a natural flow of water moving across country between banks. It is smaller than a river.
The primary meaning of stream is a body of water, confined within a bed and banks, and having a detectable current. Synonyms or related words include river, creek, tributary, run, branch, brook, even washes and forks. Navigable streams are sometimes called waterways, though the term may apply to any size of permanent and natural water feature except oceans.
In the United States, an intermittent stream is one that only flows for part of the year and is marked on topographic maps with a line of blue dashes and dots.
Generally, streams that form only during and immediately after precipitation are termed ephemeral streams.
When a stream flows over an especially resistant rock layer and forms a waterfall or cascade, the resulting sudden change in stream elevation is called a nickpoint.
Meanders are looping changes of direction of a stream. Typically, over time, the meanders don’t disappear but gradually change and move farther downstream. However, if some resistant material slows or stops the movement of a meander, a stream may erode through the neck between two legs of a meander to become temporarily straighter, leaving behind an arc-shaped body of water termed an oxbow lake or bayou. A flood may also result in a meander being cut through in this way.
Look at how the river has turned in the picture above and, in the process, parts of it have been cut off.
It gets its name from the oxen harness. Here’s a picture of that.
The point of origin of a stream is often called the headwaters or source. The entire basin drained by the stream is termed the watershed.
The Mississippi River watershed includes the Ohio River watershed, which in turn includes the Kentucky River watershed, and so forth.
The point at which a stream empties into an ocean or other large body of relatively level water is termed the mouth. There may often be an estuary or delta at the mouth.
Some streams flow underground through unconsolidated sediments or through caves. Especially with caves, a stream may flow above ground for part of its course, and underground for part of its course. When a stream emerges from an underground course, it is termed a spring.