"The group of individuals susceptible to the event of interest (e.g., infection, disease, death) at or during the time period of interest. The population at risk is used as the denominator in calculations of measures of disease frequency and can include the entire population or only a population subset, depending on susceptibility or specific interest in certain subgroups."
Definition Source: https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/at-risk-population
a.k.a. population at risk, populations at risk, at risk population
312