Confluence
Etymology
From Latin "confluere" ("to flow together"), from "con-" ("together") and "fluere" ("to flow"). The same "fluere" gives us fluid, influence, and fluent.
noun · /KON-floo-ence/
The point where two rivers or streams flow together into one; more broadly, a merging of things.
What it names
It gives a precise word for a junction of flows — and a common metaphor for the coming-together of ideas, forces, or events.
Example
The city grew at the confluence of the two rivers.
Related idea
A tributary is the smaller stream feeding a larger river; the confluence is the exact spot where the joining happens.