Dictionary · Standards & Units
Off-system measurement unit
A unit that does not belong to the system of units in use — the day, the electronvolt, and the nautical mile relative to the SI.
Related terms
More from Standards & Units
Derived unit
A measurement unit for a derived quantity, formed as a product of powers of base units — the newton (kg·m·s⁻²) or the pascal (N/m²).
VIM (JCGM 200:2012) 1.11
Reference data
Data related to a property of a phenomenon, body, or substance — or to a system of components of known composition or structure — obtained from an identified source, critically evaluated, and verified for accuracy.
VIM (JCGM 200:2012) 5.16
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
Unit equation
A mathematical relation between base and derived units — N = kg·m·s⁻².
VIM (JCGM 200:2012) 1.23
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
Multiple of a unit
A unit obtained by multiplying a given unit by an integer greater than one — the kilometre from the metre.
VIM (JCGM 200:2012) 1.17