define at risk
at risk, the state of an individual or population being vulnerable to a particular disease or event. The factors determining risk may be environmental, psychosocial, psychologic, or physiologic. An example of an environmental factor is exposure to harmful substances or organisms.t risk, the state of an individual or population being vulnerable to a particular disease or event. The factors determining risk may be environmental, psychosocial, psychologic, or physiologic. An example of an environmental factor is exposure to harmful substances or organisms.