Chance of something happening, whether defined, measured or estimated objectively or subjectively, or in terms of general descriptors (such as rare, unlikely, likely, almost certain), frequencies, or probabilities. Sample Usage: The likelihood of natural hazards can be estimated through the examination of historical data. Annotation: (1) Qualitative and semi-quantitative risk assessments can use qualitative estimates of likelihood such as high, medium, or low, which may be represented numerically but not mathematically. Quantitative assessments use mathematically derived values to represent likelihood. (2) The likelihood of a successful attack occurring is typically broken into two related, multiplicative quantities: the likelihood that an attack occurs (which is a common mathematical representation of threat), and the likelihood that the attack succeeds, given that it is attempted (which is a common mathematical representation of vulnerability). In the context of natural hazards, likelihood of occurrence is typically informed by the frequency of past incidents or occurrences. (3) The intelligence community typically estimates likelihood in bins or ranges such as "remote”, "unlikely, " "even chance, " "probable/likely, " or "almost certain.‖ (4) Probability is a specific type of likelihood. Likelihood can be communicated using numbers (e.g. 0-100, 1-5) or phrases (e.g. low, medium, high), while probabilities must meet more stringent conditions. See Also: probability