The em dash, also known as a long dash, is a punctuation mark that's commonly used in writing. However, there are several other terms commonly used to refer to it. One of the most popular synonyms is the dash itself, but there are other terms like the long dash, mutton dash, and double hyphen. Each term refers to the same punctuation mark, which is used to indicate a break in thought or a shift in tone. Regardless of the terminology you use, the em dash remains a powerful tool used by many writers to convey emphasis or provide structure to their sentences.