I believe it is refered to as "confluence".
Two rivers partially form Illinois State's Eastern boundary. The Wabash River is one river that forms Illinois' boundary. The Ohio River is the other river that forms the state's boundary.
The two rivers that form the Ohio River are the Alleghenyand Monongahela rivers.
Blue Nile or White Nile
The Yalu River and the Tumen River form the northern border of North Korea.
One rides over the other to form an occluded front.
Two rivers that join the Mississippi River are the Missouri River and the Ohio River.
There is not just one place where two heads of water join to form another body of water. The White Nile and Blue Nile come together to form the Nile river.
The Yalu River and the Tumen River form the northern border of North Korea.
They form an embryo
The Ganges river was formed when the two rivers - Bhagirathi and Rudraprayag met at Devprayag to form the main River.
The Monongahela River, and Allegheny River points meet to form the Ohio River.
There is no such river called the Murray Darling.The Murray River forms part of the border between Victoria and New South Wales in Australia.The two rivers, the Murray and the Darling, together form Australia's biggest river system, but they are two separate and distinct rivers.The Darling River is a tributary of the Murray.