The Lorentz Factor, denoted by a lower-case Greek letter gamma, ${\gamma}$ , is fundamental to Einstein's Special Relativity.

It is defined by

${\gamma}=\frac{1}{\sqrt{1-\frac{v^2}{c^2}}}$

where $v$ is the velocity of a moving frame relative to an inertial reference frame and $c$ is the speed of light.