The art and practice of conducting international relations by negotiating alliances, treaties, agreements etc., bilaterally or multilaterally, between states and sometimes international organizations, or even between polities with varying status, such as those of monarchs and their princely vassals.
Tact and subtle skill in dealing with people so as to avoid or settle hostility.
A place where powerful people meet to decide a matter in secret, often of a political nature.
Used other than figuratively or idiomatically: see smoke, filled, room.