Interna'tional Sys'tem of U'nits
an internationally accepted coherent system of physical units, derived from the MKSA system, using the meter, kilogram, second, ampere, kelvin, mole, and candela as the basic units (SI units) of the fundamental quantities length, mass, time, electric current, temperature, amount of substance, and luminous intensity. Abbr.: SI
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.