International System of Units
noun
A system of physical units (SI units) based on the metre, kilogram, second, ampere, kelvin, candela, and mole, together with a set of prefixes to indicate multiplication or division by a power of ten.The modern international system of units includes the Gray, the Sievert, and the Becquerel (Bq); these replace the rad, rem, and Curie, respectively.
Origin
Translating French Système International d'Unités.