Fr.: facteur de Lorentz
In → special relativity, an important parameter which appears in several equations, including → time dilation, → length contraction, and → relativistic mass. It is defined as γ = 1 / [1 - (v/c)2]1/2 = dt/dτ, where v is the velocity as observed in the reference frame where time t is measured, τ is the proper time, and c the → velocity of light. Same as Lorentz γ factor.