"system of units"@en . . "In order to achieve a coherent, interdependent set of units of measure in the wide variety of units that exist, units are organised in systems of units. A system of units is based on a set of units chosen by convention to be the system\u2019s base units, units that are considered to be mutually independent (i.e., can\u2019t be expressed in terms of each other)."@en .