The continuing arrangement of persons in relationships defined or controlled by institutions, ie, socially established norms or patterns of behaviors.
Radcliffe-Brown, Alfred Reginald. Method in social anthropology: Selected essays. University of Chicago Press, 1958:177
Social structure can be defined as the multidimensional space of different social positions among which a population is distributed.
Blau, Peter Michael. Inequality and heterogeneity: A primitive theory of social structure. New York: Free Press, 1977:4
Persisting and bounded pattern of social relationships (or pattern of behavioral interaction) among the units (that is, persons or positions) in a social system.
House, J.S., "Social Structure and Personality". In: Rosenberg, M., Turner, R.H. (Eds.), Social Psychology. Basic Books, Inc., New York, pp. 525–561. 1981:542