The term "number sign" has several synonyms depending on the context. In music notation, it is called a sharp symbol. In the world of social media, it is referred to as a hashtag or pound sign. In telephone terminology, it is often called a pound key or pound sign. In some countries, it is known as an octothorpe. Additionally, the symbol is used in mathematical equations where it can stand for different operations, such as multiplication and cross product. Understanding these various synonyms can help individuals properly communicate in specialized fields and across different platforms.