The term "solidus" has multiple meanings depending on the context. In mathematics, it refers to a symbol (/) used to represent division or fractions, often called a "slash." It can also denote a specific type of line in geometry, indicating a boundary or separation between different areas. In historical contexts, the solidus was a gold coin used in the Roman Empire, introduced by Emperor Constantine the Great in the 4th century. This coin became a standard for trade and commerce, influencing the development of currency in Europe and beyond.