Define fundamental quantity.

A fundamental quantity is a physical quantity that is independent of other quantities and cannot be defined in terms of other physical quantities. These quantities are considered to be the building blocks of the measurement system and are used as the basis for deriving other quantities. Examples of fundamental quantities include length, mass, time, electric current, temperature, amount of substance, and luminous intensity.

A fundamental quantity is a quantity that can be expressed independently of any other quantity. In other words, it is a quantity that cannot be derived from any other quantity.

The seven fundamental quantities in the International System of Units (SI) are:

- Length
- Mass
- Time
- Electric current
- Temperature
- Amount of substance
- Luminous intensity