|physics any of the fundamental units in a system of measurement. The base SI units are the metre, kilogram, second, ampere, kelvin, candela, and mole|
|one of a set of unrelated units that form the basis of a system of units. For example, the metre, kilogram, and second are fundamental units of the SI system|
base unit n.
Any of the fundamental units of length, mass, time, electric current, thermodynamic temperature, amount of substance, or luminous intensity in the International System of Units, consisting respectively of the meter, kilogram, second, ampere, kelvin, mole, and candela.