Secretary-General

Secretary is a title often used in organizations to indicate a person having a certain amount of authority, power, or importance in the organization. Secretaries announce important events and communicate to the organization. The term is derived from the Latin word secernere, "to distinguish" or "to set apart", the passive participle (secretum) meaning "having been set apart", with the eventual connotation of something private or confidential, as with the English word secret. A secretarius was a person, therefore, overseeing business confidentially, usually for a powerful individual (a king, pope, etc.).

The official title of the leader of most Communist and Socialist political parties is the "General Secretary of the Central Committee" or "First Secretary of the Central Committee". When a Communist party is in power, the General Secretary is usually the country's de facto leader (though sometimes this leader also holds state-level positions to monopolize power, such as a presidency or premiership in order to constitute de jure leadership of the state), such as China and Cuba.

In England, the term secretarius was used "from the beginning of the thirteenth century in the varying meanings of a confidential clerk, an ambassador, or a member of the king's council". In the fourteenth century, the title became strongly associated with the keeper of the king's signet. From the Renaissance to the late 19th century, men involved in the daily correspondence and the activities of the powerful assumed the title of secretary. With time, like many titles, the term was applied to more and varied functions, leading to compound titles to specify the authority associated with its use, like general secretary or financial secretary.

In some countries, such as the United States, the term secretary is used to indicate the holder of a cabinet-level post. This usage derives in part from the desire of the founders of the United States to differentiate the country from the United Kingdom, which denoted such offices as Ministers. There are a number of popular variations of the title used to indicate that the secretary in question has a high degree of authority, such as general secretary (or, following usage in the Norman language, secretary-general), first secretary, and executive secretary.

...
Wikipedia