S.I. units. A system of units of measurement based on the metric system, adopted and described by the Eleventh General Conference on Weights and Measures. It involves seven base units:
(1) meter for length;
(2) kilogram for mass;
(3) second for time;
(4) Kelvin for temperature;
(5) ampere for electric current;
(6) candela for luminous intensity; and
(7) mole for amount of substance.