What is the meaning of Derived_unit?

(In the SI system of units) Any unit derived from one of the seven base units of length (meter), mass (kilogram), time (second), electric current (ampere), thermodynamic temperature (kelvin), amount of substance (mole) and luminous intensity (candela).

Equivalently, in any coherent unit system, a unit derived from one or more base units.

Source: wiktionary.org