regentship

adjective

1. acting in place of a king or ruler: a prince regent
2. Now Rare acting as ruler; ruling

noun

1. a person appointed to rule a monarchy when the sovereign is absent or too young or incapacitated to rule
2. ☆
   1. a member of the governing board of certain institutions, as of a state university or a state system of schools
   2. any of certain other university officers
3. Now Rare a ruler; governor