In biostatistics, hazard, or the hazard rate, is the instantaneous rate of an event (death, failure…). It is the probability of the event occurring in a (vanishingly) small period of time, divided by the amount of time (mathematically it is the limit of this quantity as the time period goes to 0). The division by a time period means that hazard is not a probability, and is not limited to the range between 0 and 1.
