A staffing supplier that takes overall responsibility for providing clients with temporary staff. In a master supplier relationship, all orders will usually go first to the master supplier to either be filled or distributed to secondary suppliers. Sometimes a master supplier will not only provide a significant portion of the temporary staff working at the employer’s site but also manage an organization’s contingent workforce program. Also known as Master Vendor. (See also: Vendor on Premises.)
Source: Staffing Industry Analysts