Noun

1. An order or mission which presents the overriding control over a course of action.

   1955: René Albrecht-Carrié, Europe After 1815, p. 32:

   • The prime directive of Austrian policy was the preservation of this state of affairs.

   1946: University of Iowa/University of Chicago, The Journal of General Education, p. 160:

   • Such probes would not invalidate the prime directive that a work of art must stand upon its intrinisic artistic merits

   1902: University of Michigan Law School, Michigan Law Review p. 1949:

   • We are, after all, discussing the prime directive of academic life and a vitally important rule of civilized life in general: Seek and disseminate the truth.