System of measurement

A system of measurement is a set of related measures that are used to give a numeric value to something. A "system of measurement" is also known as a "metric". There are many systems of measurement. Some systems of measurement describe physical systems. Other systems of measurement describe economic systems.
The term "system of measurement" is often used in engineering application to describe a set of operational devices that take measurements. 
In metrology, the term "system of measurement" is often used as a synonym for system of units.
The international standard system is the International System of Units. Other systems in common use are the closely related United States customary units and British imperial units. 
A system of measurement that describes economic systems is called an econometric system. An econometric system uses quantities such as Gross domestic product and money supply to model an economic system.