Definition 2: Relative frequency of repeated event

For repeated events, probability can be estimated by the ``long-run'' relative frequency of an event out of a set of many trials. If an event occurs $m$ times in $n$ trials then the relative frequency $m/n$ provides an unbiased estimate of the probability of the event. In the asymptotic limit as the number of trials $n$ tends to infinity, the relative frequency converges to the true probability of the event (``Law of large numbers''). This interpretation involving repeated trials is known as the ``frequentist'' approach to probability.