Premier

Premier is a title for the head of government in some countries, states and sub-national governments. A second in command to a premier is designated as a vice-premier or deputy premier.
Examples by country.
The word comes from french "Premier ministre" which means prime minister. "Premier" meaning "first", coming from Latin prīmārius. This is why in many nations, "premier" is used interchangeably with "prime minister".
In the People's Republic of China, "premier" is more common and official, but "prime minister" is still used (see Premier of the People's Republic of China).
In five of the British overseas territories (Bermuda, the Cayman Islands, Montserrat, the Turks and Caicos Islands, and the British Virgin Islands), the elected heads of government are styled as "Premier". In other overseas territories the equivalent post is styled as Chief Minister.
"Premier" is also the title of the heads of government in sub-national entities, such as the provinces and territories of Canada, states of the Commonwealth of Australia, provinces of South Africa, the island of Nevis within the Federation of Saint Kitts and Nevis, and the nation of Niue. In some of these cases, the formal title remains "Prime Minister" but "Premier" is used to avoid confusion with the national leader. In these cases, care should be taken not to confuse the title of "premier" with "prime minister". In these countries, terms such as "Federal Premier", "National Premier" or "Premier of the Dominion" were sometimes used to refer to prime ministers, although these are now obsolete. 
In Cambodia, "Premier" means the "Prime Minister". In Federation of Bosnia and Herzegovina, sub-national entity of Bosnia and Herzegovina, as well in cantons, head of government have formal title of "premier", often anglicized as "prime minister", while national prime minister is Chairman of the Council of Ministers of Bosnia and Herzegovina, but "premier" is sometimes colloquially used.
In the Czech Republic, "Premiér" means the "Prime Minister" and the Czech language translates both "Premier" and "Prime Minister" as "Premiér".
In Croatia, the head of government is officially called "President of the Government" ("predsjednik vlade") but "Premier" ("premijer") is colloquially used.
In Serbia, the head of government is officially called "President of the Government" ("predsednik vlade") but "Premier" ("premijer") is colloquially used.
In Italy, the President of the Council of Ministers, an office equivalent to prime minister, is informally referred to as the "Premier".
In North Macedonia the head of the government is named premier (Macedonian премиер, "premier"), usually translated in English as prime minister.
A premier will normally be a head of government, but is not usually the head of state. In presidential systems, the two roles are often combined into one, whereas in parliamentary systems of government the two are usually kept separate. 
An example of nations that have separate roles for the premier/prime minister and the president are the Fifth French Republic, South Korea and China.
In the Soviet Union, the title of premier was applied to the Chairman of the Council of People's Commissars (Renamed "Council of Ministers of the USSR" in 1946) who acted as the Soviet Union's Premier.