Princeton's WordNet

1. Systeme International d'Unites, Systeme International, SI system, SI, SI unit, International System of Units, International System(noun)

   a complete metric system of units of measurement for scientists; fundamental quantities are length (meter) and mass (kilogram) and time (second) and electric current (ampere) and temperature (kelvin) and amount of matter (mole) and luminous intensity (candela)

   "Today the United States is the only country in the world not totally committed to the Systeme International d'Unites"