CMN is an acronym that is commonly used in the business world to refer to a "common message note". The term CMN refers to a document that outlines a message or communication that needs to be shared among multiple parties. There are several synonyms that can be used for the term CMN including memorandum, memo, note, record, communication, correspondance, and message. While these terms may be used interchangeably, they all have slightly different connotations. A memorandum, for example, may be used to communicate a more formal message, while a note may be a brief message that is less formal. Regardless of the specific terminology used, CMNs are an important tool for businesses to ensure that information is communicated effectively and efficiently.