Dictionary · Standards & Units
Measurement standard (etalon)
The realization of the definition of a given quantity, with stated value and uncertainty, used as a reference — an artifact, instrument, reference material, or measuring system.
Related terms
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Conservation of a measurement standard
The set of operations necessary to preserve the metrological properties of a standard within stated limits — storage, handling, surveillance, and use discipline.
VIM (JCGM 200:2012) 5.11
International System of Quantities (ISQ)
The system of quantities based on the seven base quantities: length, mass, time, electric current, thermodynamic temperature, amount of substance, and luminous intensity — the quantity framework beneath the SI.
VIM (JCGM 200:2012) 1.6
System of quantities
A set of quantities together with the non-contradictory equations relating them — the framework a system of units is built on.
VIM (JCGM 200:2012) 1.3
Base quantity
A quantity in a conventionally chosen subset of a system of quantities in which no member can be expressed in terms of the others.
VIM (JCGM 200:2012) 1.4
Ordinal quantity
A quantity defined by an agreed procedure that can be ranked but has no meaningful algebra — Rockwell hardness or earthquake magnitude: order exists, differences and ratios do not.
VIM (JCGM 200:2012) 1.26
Quantity dimension
The expression of a quantity's dependence on the base quantities as a product of powers of their dimensions — force has dimension L·M·T⁻².
VIM (JCGM 200:2012) 1.7