Interregnum
Etymology
Directly from Latin, inter ("between") plus regnum ("reign, rule"): the interval between reigns. It originally described the pause between one monarch’s death and the next’s accession. The word now covers any lapse in continuous authority, from a leaderless government to a broader era of uncertain power.
noun · /in-ter-REG-num/
A period between two reigns or governments, when normal authority is suspended or in transition.
What it names
It marks the revealing gap when the old order has lost its grip and the new one has not yet taken hold — a moment when hidden forces surface.
Example
In the interregnum between the collapse of one cabinet and the swearing-in of the next, the bureaucracy quietly ran the country.
Related idea
An interregnum is the vacancy between reigns; a "regency" fills such a gap with a stand-in ruler for an absent or underage monarch. The first names the emptiness, the second names the arrangement that plugs it.