A chief minister is an elected or appointed head of government of – in most instances – a sub-national entity, for instance an administrative subdivision or federal constituent entity. Examples include a state (and sometimes a union territory) in India; a territory of Australia; a province of Sri Lanka or Pakistan; a federal province in Nepal; an autonomous region of Philippines; or a British Overseas Territory that has attained self-governance. It is also used as the English version of the title given to the heads of governments of the Malay states without a monarchy.
In 2018 Sierra Leone, a presidential republic, created the role of an appointed Chief Minister, which is similar to a Prime Minister in a semi-presidential system. Before that, only Milton Margai had the same position between 1954 and 1958.
The title has a similar construction and role as a prime minister, first minister or minister-president but usually with a lower rank. The role has context within the Westminster system of government where a constitutional head of state (usually sub-national) is advised by ministers who usually head executive government departments (ministries). A chief minister is understood to be "first among equals". They would be the chief adviser to the nominal head of their state, the chair of cabinet and leader of the main governing political party in the legislature.