noun
regent
REE-junt/ˈriːdʒənt/
A person governing temporarily in place of a monarch.
The regent receives council papers beside the unoccupied throne.

Etymology
Originally describing someone ruling or governing, regent narrowed to a person exercising authority in a sovereign’s place. The title identifies the ruler’s temporary role without implying permanent possession of the throne.
In context
at 16 Alexander was left in charge of Macedon as Regent or acting ruler while Philip went away to war
More examples
- The queen's brother serves as regent while she is abroad.
- A regent governs until the young king is old enough to rule.
- The king's illness forces the council to appoint a regent.
Forms
regent · regents
regency noun — The office or period of a regent's rule.
Similar words
- ruler
- A broader term that does not imply temporary authority.
- governor
- Usually governs a territory rather than temporarily replacing a monarch.