prime minister 
noun
The head of an elected government; the principal minister of a sovereign or state: [as title]: the Japanese prime minister argued strongly against it Prime Minister Albert Reynolds...
- There have been many mutual visits, by presidents, prime ministers and foreign ministers.
- The prime ministers of Italy, Spain and the United Kingdom were elected.
- Since the 1980s, the Antilles has had two female prime ministers and several female ministers.
Synonyms
premier, first minister, head of the government;
British First Lord of the Treasury
In current use, the terms Premier and Prime Minister refer to the same office in Britain, but in Canada and Australia the government of a province or state is headed by a Premier, that of the federal government by a Prime Minister. In countries such as France, where the President has an executive function, the Prime Minister is in a subordinate position.