Definition:
Power Distance Index (PDI) measures the extent to which the less powerful members of organizations and institutions accept and expect that power is distributed unequally. It is primarily used in psychological and sociological studies on societal management of inequalities between individuals, and individual’s perceptions of that management.
In lower PDI cultures, the emotional distance is relatively small. There are more democratic or consultative relations between expecting and accepting power. People are relatively interdependent to the power holders, and there is relatively low inequality of power distributed among the people. In high PDI Cultures the power relations are paternalistic and autocratic, and where there is centralized authority. In other words, there is a wide gap or emotional distance which is perceived to exist among people at different levels of the hierarchy.
Further Reading:
BOOK: SUCCEEDING WITH AGILE Software Development Using Scrum by Mike Cohn
https://en.wikipedia.org/wiki/Power_distance