# Definition:Magnitude

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## Definition

The magnitude (or size) of a quantity (either vector or scalar) is a measure of how big it is.

It is usually encountered explicitly in the context of vectors:

If $\mathbf v$ is the vector quantity in question, then its magnitude is denoted:

$\size {\mathbf v}$

or

$v$

## Also defined as

In Euclidean number theory, the term magnitude is used to mean positive real number.

## Also known as

The magnitude of a vector is also referred to as its module or modulus in some older books.

Some sources refer to it as the absolute value of the vector.

## Sources

in which context it is applied to a force only