A prime minister is a politician who heads a cabinet, whether in a parliamentary or autocratic government. The role of prime minister is also variously described by such terms as first minister, premier, chief minister, president of the executive council and primus inter pares (first among equals).
Some characters are prime ministers. In parliamentary government, the role of prime minister is typically of great importance; in presidential government, the role is typically of much lesser importance; and in mixed or other systems, the role varies greatly in importance.
Primus inter pares
Historically, prime ministers have often been referred to as Primus inter pares, a Latin term translated as First Among Equals, and which reflects the original concept of a prime minister as merely the first minister or most senior minister to the monarch, not the dominant or presiding minister, a role later assumed by many prime ministers in many, but not all, states.