A quality management system, or QMS, is a set of documented policies, procedures, processes and responsibilities organized into a structured collection to facilitate a business or organization realizing its quality vision, goals and objectives.
Standards Council of Canada:
"A quality management system (QMS) defines and establishes an organization's quality policy and objectives. It also allows an organization to document and implement the procedures needed to attain these goals."
ASQ (formerly American Society for Quality): "Quality management system (QMS): A formalized system that documents the structure, responsibilities and procedures required to achieve effective quality management."