Addressor is a term that refers to a person or entity that sends a message or letter to another person or entity. However, there are several synonyms for the word "addressor" that can be used interchangeably in different contexts. These synonyms include sender, writer, originator, and correspondent. The word "sender" is commonly used to refer to the person who sends an email or a package, while "writer" is used to describe the person who pens a letter or note. "Originator" is a term that emphasizes the person who initiates a message, and "correspondent" usually refers to someone who regularly communicates with another person or entity.