group
n. any collection or assemblage, particularly of items or individuals. For example, in social psychology the term refers to two or more interdependent individuals who influence one another through social interactions that commonly include structures involving roles and norms, a degree of cohesiveness, and shared goals. Such social groups thus are contrasted with aggregations. Similarly, in animal behavior, a group refers to an organized collection of individuals that moves together or otherwise acts to achieve some common goal (e.g., protection against predators) that would be less effectively achieved by individual action, and in research, it denotes a collection of participants who all experience the same experimental conditions and whose responses are to be compared to the responses of one or more other collections of research participants.