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https://en.wikipedia.org/wiki/Dimensional_analysis

Definition

The dimension of a physical quantity can be expressed as a product of the basic physical dimensions
such as length, mass and time, each raised to a rational power.

The dimension of a physical quantity is more fundamental than some scale unit
used to express the amount of that physical quantity.

For example, mass is a dimension, while the kilogram is a particular scale unit
chosen to express a quantity of mass.
Except for natural units, the choice of scale is cultural and arbitrary.