Meaning of “SI” in the English Dictionary

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"SI" in American English

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SInoun [ U ]


science abbreviation for International System of Units (= an international system of units used for measurement in scientific work)

(Definition of “SI” from the Cambridge Academic Content Dictionary © Cambridge University Press)

"SI" in Business English

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uk /ˌesˈaɪ/ us MEASURES

abbreviation for Système International: a system of units of measurement used internationally. SI units include the metre, kilogram, second, ampere (= unit of electric current), candela (= unit of light), kelvin (= unit of temperature), and the mole (= unit of the amount of a substance):

The chart shows you how to convert from a conventional unit to an SI unit.

UK LAW →  statutory instrument

(Definition of “SI” from the Cambridge Business English Dictionary © Cambridge University Press)