many-to-many adjective2 •Having the property that many elements of one set may be assigned by the relationship to any element in the other set, and that a given element in the first set can also be assigned more than one member of the second set."Is a fellow citizen with" is a many-to-many relationship on the set of people (from the set of people to the set of people). •From many sources to many recipients.The normal state of human affairs is many-to-many communications, each source going out to many recipients, but each recipient also having multiple sources.