A reign is a period of time a person serves as a monarch or pope. No time limit exists on reigns, nor is there a term of office. Thus a reign usually lasts for the remainer of the monarch's life, unless the monarchy itself is abolished or the monarch abdicates.
The term of a reign can be indicated with the abbreviation "r." after a sovereign's name, such as the following:
A reign can be ended in three ways:
King Constantine II of Greece reigned from 1963 until the abolition of the Greek monarchy in 1973.
King Humbert II of Italy reigned for only a few weeks in 1946 before the abolition of the Italian Monarchy.