base unit

noun Physics.

1. one of the units, as mass, length, time, or electric current, taken as a basis for a system of units in the sciences.

noun

1. 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

n.

1. 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.