IEVref:112-02-05ID:
Language:enStatus: Standard
Term: metre
Synonym1: meter, US
[Preferred]
Synonym2:
Synonym3:
Symbol: m
Definition: SI unit of length, equal to the length of the path travelled by light in vacuum in a duration of 1/299 792 458 s

Note 1 to entry: The definition in the SI Brochure is: "The metre, symbol m, is the SI unit of length. It is defined by taking the fixed numerical value of the speed of light in vacuum c to be 299 792 458 when expressed in the unit m s−1, where the second is defined in terms of the caesium frequency ΔνCs."

Note 2 to entry: The metre is one of the seven SI base units: second (s), metre (m), kilogram (kg), ampere (A), kelvin (K), mole (mol) and candela (cd).


Publication date:2020-12
SourceSI Brochure, 9th edition, 2019, 2.3.1, modified – The definition in the SI Brochure has been revised to comply with the IEV rules. Notes 1 and 2 to entry have been added.
Replaces:112-02-05:2010-01
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