What term describes the flowing together of two or more streams?

The term that describes the flowing together of two or more streams is "confluence." Confluence refers specifically to the point where two or more bodies of water meet and flow together, creating a single stream. This term is commonly used in geography and hydrology to denote the merging of rivers or streams. It reflects not only the physical coming together of the waters but also can imply a blending of their characteristics, such as flow rate, temperature, and sediment load.

The other options do not pertain to this specific geological process. Correlation relates to the relationship between variables or phenomena, consternation refers to feelings of anxiety or dismay, and cornucopia symbolizes abundance or a source of plenty, often depicted as a horn overflowing with produce. These definitions highlight why "confluence" is the correct term for the merging of streams.