si unit meaning and definition

SI UNIT noun

Definition of SI unit (noun)

1. 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"
   • synonyms: International System, International System of Units, SI, SI system, Systeme International, Systeme International d'Unites