What does 'likelihood' refer to in the context of risk assessment?

In the context of risk assessment, 'likelihood' specifically refers to the probability of an event occurring and how often that event may happen. This encompasses both the chance of the occurrence and the expected frequency of that occurrence over a certain time period or under specified conditions.

Understanding likelihood is critical in risk management as it helps organizations prioritize risks based on how probable they are to happen. When assessing risks, it's vital to consider not just whether an event could happen, but how often it might occur and the real-world implications of that frequency.

In risk assessment, the other concepts—certainty of an outcome, impact of an outcome, and severity of a potential risk—are important, but they focus on different aspects. Certainty pertains to how assured you are about an outcome, impact relates to the consequences if the event occurs, and severity describes the degree of harm or loss that could result. However, these do not define likelihood, which is inherently about the probability and frequency aspects of potential events. Therefore, the answer highlighting likelihood as the probability of an event along with its frequency is the most accurate in this context.