in·ter·reg·num 
(ĭn′tər-rĕgnəm)
(ĭn′tər-rĕgnəm)n. pl. in·ter·reg·nums or in·ter·reg·na (-nə)
1. The interval of time between the end of a sovereign's reign and the accession of a successor.
2. A period of temporary suspension of the usual functions of government or control.
3. A gap in continuity.
[Latin : inter-, inter- + rēgnum, reign; see REIGN.]
in′ter·regnal (-nəl) adj.