Since defining quality so it will be accepted from company to company is a difficult task. This paper will discuss definitions of quality and how metrology can assist a company in defining its' quality. The title; Metrology:A Definition of Quality implies an explanation of how metrologists thinking has become important to companies committed to quality. This paper discusses the advantages quality programs derive from having metrology heavily involved in their processes and procedures. This paper also talks about the changing role of metrologists from strictly calibrating of the test equipment to applying process metrology in order to ensure the overall quality of the products.