Longman Dictionary of Contemporary English
Wiktionary
n. 1 The senior officer of any of several services of the armed forces of several nations. 2 The head of any of several political departments in several nations.
WordNet
n. the senior officer of a service of the armed forces
Wikipedia
The title chief of staff identifies the leader of a complex organization, institution, or body of persons and it also may identify a principal staff officer (PSO), who is the coordinator of the supporting staff or a primary aide-de-camp to an important individual, such as a president or a senior military officer.
In general, a chief of staff provides a buffer between a chief executive and that executive's direct-reporting team. The chief of staff generally works behind the scenes to solve problems, mediate disputes, and deal with issues before they are brought to the chief executive. Often chiefs of staff act as a confidante and advisor to the chief executive, acting as a sounding board for ideas. Ultimately the actual duties depend on the actual position and the people involved.
The Chief of Staff of the Philippines, also known as Malacañang Chief of Staff, was an official position under the Office of the President of the Philippines. President Joseph Estrada created the position in February 2000, but described it as only being a "temporary" position. However, this position was carried over to the administration of his successor, President Gloria Macapagal-Arroyo, before being abolished in February 2008.
The Chief of Staff of Ghana is the coordinator of the supporting staff and the primary aide-de-camp of the President of Ghana.
The Chief of Staff (COS) is an appointed executive branch official in the Government of Rivers State responsible for coordinating the operations of the Governor's office as well as assisting the Chief Executive in the management of affairs of the government. The Chief of Staff oversees members of the Executive Council and serves as the Governor's liaison with the state executive branch.
Other responsibilities include preparation of the Governor's daily schedule, organisation of meetings, arbitration of disputes, regulation of gubernatorial access.