The phrase "Forth River" refers to the river that flows through the city of Edinburgh in Scotland. There are a number of synonyms that can be used to describe this body of water, such as the River Forth, Fourth River, and Forth Estuary. These terms are often used interchangeably to refer to the same river. The River Forth is one of the most significant bodies of water in the region, and it has played a vital role in the history and development of Edinburgh and the surrounding area. Whether you use the term Forth River, River Forth, or another synonym, this is a body of water that has a rich cultural and historical significance.