The phrase "someone else" refers to another person or people who are not the speaker or the person being referred to in a conversation. There are many synonyms for this phrase, including "another person," "a different individual," "someone other than oneself," "another party," "a stranger," and "an outsider." These phrases can be used in various situations to replace the term "someone else" and add variety to a piece of writing or conversation. Using synonyms can also help in avoiding repetition and ensuring clear and concise communication.