Dictionary · Standards & Units
Reference measurement standard
A standard designated for the calibration of other standards for quantities of a given kind in an organization or at a location — a laboratory's best standard.
Related terms
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Reference quantity value
A quantity value used as a basis for comparison with values of quantities of the same kind — a true value, a conventional value, or a standard's certified value, depending on context.
VIM (JCGM 200:2012) 5.18
Commutability of a reference material
The property demonstrated by the closeness of agreement between the relation among results for a stated quantity in the RM and the relation among results for representative routine samples, across specified procedures — whether the RM behaves like the real thing.
VIM (JCGM 200:2012) 5.15
Conversion factor between units
The ratio of two units for quantities of the same kind — 25.4 mm/in; the numerical value changes, the quantity does not.
VIM (JCGM 200:2012) 1.24
Measurement unit
A real scalar quantity, defined and adopted by convention, with which any other quantity of the same kind is compared to express the ratio of the two quantities as a number.
VIM (JCGM 200:2012) 1.9
International System of Units (SI)
The system of units based on the ISQ, with unit names, symbols, prefixes, and rules for their use, adopted by the CGPM. Since the 2019 revision all seven base units are defined by fixing the numerical values of seven defining constants.
VIM (JCGM 200:2012) 1.16
System of units
A set of base and derived units, with their multiples and submultiples, defined under given rules for a given system of quantities.
VIM (JCGM 200:2012) 1.13