• Abbreviation of Système International d'unités. French for International System of Units. A system utilized for measurement of physical quantities using internationally accepted fundamental units which are defined in an absolute manner. Currently, the base, or fundamental, SI units are: the second, for time; the kilogram, for mass; the meter, for distance; the ampere, for electric current; the kelvin, for temperature; the mole, for amount of substance; and the candela, for luminous intensity. In addition, there are other units defined algebraically in terms of these base units. These include hertz, joule, watt, coulomb, volt, and ohm. Furthermore, the SI allows the use of certain non-approved units, such as electronvolt, bel, and angstrom.
  • chemical symbol for silicon
    (written as Si)
  • acronym for Système International d'Unités

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