# Definition:Dimension (Measurement)

## Definition

Every physical quantity has a dimension associated with it.

No attempt is made here to provide an abstract definition of this term. Instead, it will be defined by example.

## Fundamental Dimensions

The fundamental dimensions are:

• Mass, denoted $M$ or $\mathbf M$
• Length, denoted $L$ or $\mathbf L$
• Time, denoted $T$ or $\mathbf T$

It is convenient at elementary levels of physics to add:

However, it is possible to define these in terms of mass, length and time, so strictly speaking they are not fundamental, as such.

## Units

Compare with units of measurement.

This concept of dimension is more abstract than that of units, which are standard quantities of the particular dimension in question.