What is ment by a "derived unit."
http://www.physics.nist.gov/cuu/Units/units.html
A "derived unit" is a unit of measurement that is derived from the combination of base units. In the International System of Units (SI), there are seven base units, which are used to define all other units of measurement. These base units are meter (length), kilogram (mass), second (time), ampere (electric current), kelvin (temperature), mole (amount of substance), and candela (luminous intensity).
Derived units are formed by combining these base units using mathematical operations such as multiplication, division, or exponentiation. For example, the unit of speed is derived from the base units of length (meter) and time (second) and is expressed as meters per second (m/s).
The NIST (National Institute of Standards and Technology) website you provided offers more detailed information about the SI units and their definitions. It provides a comprehensive list of derived units used in different fields of science, engineering, and everyday life. It's a valuable resource for understanding the concepts and definitions of units in the SI system.