# International System of Units

(redirected from*SI system*)

Also found in: Dictionary, Thesaurus, Encyclopedia, Wikipedia.

Related to SI system: English system

## International System of Units

see si units.

## In·ter·na·tion·al Sys·tem of U·nits (SI),

,**Système International d'Unités**(in'tĕr-na'shŭn-ăl sis'tem yū'nits, sēs-tĕm' ahn-tĕr-nahs-ē'ōn-nahl' dūn'nē-tā'),

A system of measurements, based on the metric system, adopted at the 11th General Conference on Weights and Measures of the International Organization for Standardization (1960) to cover both the coherent units (basic, supplementary, and derived units) and the decimal multiples and submultiples of these units formed by use of prefixes proposed for general international scientific and technologic use. SI proposes seven basic units: meter (m), kilogram (kg), second (s), ampere (A), kelvin (K), candela (cd), and mole (mol) for the basic quantities of length, mass, time, electric current, temperature, luminous intensity, and amount of substance, respectively; supplementary units proposed include the radian (rad) for plane angle and steradian (sr) for solid angle; derived units (for example, force, power, frequency) are stated in terms of the basic units (for example, velocity is in meters per second, m s

^{-1}). Multiples (prefixes) in descending order are: exa- (E, 10^{18}), peta- (P, 10^{15}), tera- (T, 10^{12}), giga- (G, 10^{9}), mega- (M, 10^{6}), kilo- (k, 10^{3}), hecto- (h, 10^{2}), deca- (da, 10^{1}), deci- (d, 10^{-1}), centi- (c, 10^{-2}), milli- (m, 10^{-3}), micro- (μ, 10^{-6}), nano- (n, 10^{-9}), pico- (p, 10^{-12}), femto- (f, 10^{-15}), atto- (a, 10^{-18}). Proposed prefixes are zetta- (Z, 10^{21}), yotta- (Y, 10^{24}), zepto- (z, 10^{-21}), and yocto- (y, 10^{-24}). [Fr.

*Système International d'Unités*]## In·ter·na·tion·al Sys·tem of U·nits

**(SI)**(in'tĕr-nash'ŭn-ăl sis'tĕm yū'nits)

A system of measurements, based on the metric system, adopted at the 11th General Conference on Weights and Measures of the International Organization for Standardization (1960) to cover both the coherent units (basic, supplementary, and derived units) and the decimal multiples and submultiples of these units formed by use of prefixes proposed for general international scientific and technologic use. SI proposes seven basic units: meter (m), kilogram (kg), second (s), ampere (A), Kelvin (K), candela (cd), and mole (mol) for the basic quantities of length, mass, time, electric current, temperature, luminous intensity, and amount of substance; supplementary units proposed include the radian (rad) for plane angle and steradian (sr) for solid angle; derived units (e.g., force, power, frequency) are stated in terms of the basic units (e.g., velocity is in meters per second, m/sec

^{-1}). Multiples (prefixes) in descending order are: exa- (E, 10^{18}), peta- (P, 10^{15}), tera- (T, 10^{12}), giga- (G, 10^{9}), mega- (M, 10^{6}), kilo- (k, 10^{3}), hecto- (h, 10^{2}), deca- (da, 10^{1}), deci- (d, 10^{-1}), centi- (c, 10^{-2}), milli- (m, 10^{-3}), micro- (μ, 10^{-6}), nano- (n, 10^{-9}), pico- (p, 10^{-12}), femto- (f, 10^{-15}), and atto- (a, 10^{-18}). The prefix zepto (z) has been proposed for 10^{-21}.[Fr.

*Système International d'Unités*]## In·ter·na·tion·al Sys·tem of U·nits

**(SI)**(in'tĕr-nash'ŭn-ăl sis'tĕm yū'nits)

System of measurements, based on the metric, to cover both coherent units (basic, supplementary, and derived units) and the decimal multiples and submultiples of these units formed by use of prefixes proposed for general international scientific and technologic use. SI proposes seven basic units: meter (m), kilogram (kg), second (s), ampere (A), kelvin (K), candela (cd), and mole (mol) for the basic quantities of length, mass, time, electric current, temperature, luminous intensity, and amount of substance, respectively. Multiples (prefixes) in descending order are: exa- (E, 10

^{18}), peta- (P, 10^{15}), tera- (T, 10^{12}), giga- (G, 10^{9}), mega- (M, 10^{6}), kilo- (k, 10^{3}), hecto- (h, 10^{2}), deca- (da, 10^{1}), deci- (d, 10^{-1}), centi- (c, 10^{-2}), milli- (m, 10^{-3}), micro- (μ, 10^{-6}), nano- (n, 10^{-9}), pico- (p, 10^{-12}), femto- (f, 10^{-15}), atto- (a, 10^{-18}). Proposed prefixes are zetta- (Z, 10^{21}), yotta- (Y, 10^{24}), zepto- (z, 10^{-21}), and yocto- (y, 10^{-24}).[Fr.

*Système International d'Unités*]Want to thank TFD for its existence? Tell a friend about us, add a link to this page, or visit the webmaster's page for free fun content.

Link to this page: