Learn how to say Interregnums correctly in English with this tutorial pronunciation video.
Oxford dictionary definition of the word interregnum:
noun (plural interregnums or interregna /-nə/)
a period when normal government is suspended, especially between successive reigns or regimes.
(the Interregnum) the period in English history from the execution of Charles I in 1649 to the Restoration of Charles II in 1660.
an interval between the periods of office of two incumbents in a parish.
late 16th century (denoting temporary rule between reigns or during suspension of normal government): from Latin, from inter- ‘between’ + regnum ‘reign’