interregnum

An interregnum (plural interregna or interregnums) is a period of discontinuity or "gap" in a government, organization, or social order. Archetypally, it was the period of time between the reign of one monarch and the next (coming from Latin inter-, "between" and rēgnum, "reign" [from rex, rēgis, "king"]), and the concepts of interregnum and regency therefore overlap. Historically, longer and heavier interregna have been typically accompanied by widespread unrest, civil and succession wars between warlords, and power vacuums filled by foreign invasions or the emergence of a new power.

The term also refers to the periods between the election of a new parliament and the establishment of a new government from that parliament in parliamentary democracies, usually ones that employ some form of proportional representation that allows small parties to elect significant numbers, requiring time for negotiations to form a government. In the UK, Canada and other electoral systems with single-member districts, this period is usually very brief, except in the rare occurrence of a hung parliament as occurred both in the UK in 2017 and in Australia in 2010. In parliamentary interregnums, the previous government usually stands as a caretaker government until the new government is established. Additionally, the term has been applied to the United States presidential transition, the period of time between the election of a new U.S. president and their inauguration, during which the outgoing president remains in power, but as a lame duck.