A Postmaster General, in many countries, is the chief executive officer of the postal service of that country, responsible for oversight over all other Postmasters. The practice of having a government official responsible for overseeing the delivery of mail throughout the nation originated in England, where a Master of the Posts is mentioned in th...
• (n.) The chief officer of the post-office department of a government. In the United States the postmaster-general is a member of the cabinet.
Post'mas`ter-gen'er·al noun ; plural Postmasters-general . The chief officer of the post-office department of a government. In the United States the postmaster-general is a member of the cabinet. 
[n] - the official in charge of the national postal service
noun the official in charge of the national postal service