The term 'Jeans Fastener' refers to a RIVET, which is a small metal fastener with a flat head and a cylindrical stem. It is used to join two pieces of material together, such as denim fabric in the case of jeans. Rivets are usually made of steel, brass, or aluminum and are inserted into pre-drilled holes in the two pieces of material. The stem is then hammered or pressed down to form a head on the other side, creating a secure connection.