A regent, from the Roman regens "one who reigns", is the informal or sometimes formal title given to a temporary, acting head of state in a monarchy. The Oxford English Dictionary defines the term as "A person appointed to administer a State because the Monarch is a minor, is absent or is incapacitated." If the regent is holding this temporary position due to his or her position in the line of succession and thus is a member of the royal house, the term used is often prince regent or princess regent. The time in office for a regent is often called a regency, a term also used for the constitutional rules providing for the temporary upholding of the position.In a monarchy, a regent usually governs due to one of these reasons, but may also be elected to rule during the interregnum when the royal line has died out. This was the case in the Kingdom of Finland and the Kingdom of Hungary, where the royal line was considered extinct in the aftermath of World War I. In Iceland, the regent represented the King of Denmark as sovereign of Iceland until the country became a republic in 1944. In the Polish-Lithuanian Commonwealth (1569–1795), kings were elective, which often led to a fairly long interregnum. In the interim, it was the Roman Catholic Primate (the Archbishop of Gniezno) who served as the regent, termed the "interrex" (Latin: ruler "between kings" as in ancient Rome). In the small republic of San Marino, the two Captains Regent, or Capitani Reggenti, are elected semi-annually (they serve a six-month term) as joint heads of state and of government.