The way to implement a “many-to-many” relationship requires an additional table be created consisting of the primary keys from each of the entities. This additional table goes by many different names depending on who you talk to.
Association table
Bridge table
Cross-reference (xref) table
Intersection tables
Join table (perhaps most common)
Junction table
Link table, link entity
Many-to-many relationship tables
Map table
Reference table
Relationship table
Swing table
Probably the most proper (being a mathematical model) but least used is “Gerund” — so named by E.F. Codd, creator of the relational model. This term applies because an entity is functioning as a relationship.