Reign means the period of time when a king, queen, or other monarch rules over a country. Queen Elizabeth II's reign lasted 70 years, from 1952 to 2022, making her the longest-reigning British monarch in history. During her reign, she witnessed enormous changes in the world, from the end of World War II to the age of the internet.

Reign always involves some form of rule or leadership. When historians talk about “the reign of Louis XIV,” they mean the specific years when he was king of France.

People also use reign more broadly to describe when someone or something dominates a field. A chess champion might reign as the world's best player for several years. A sports team could reign supreme in their league, winning championship after championship. In this sense, to reign means to be clearly the best or most powerful in your domain.

You might hear someone say a champion's reign came to an end when they finally lost their title. The verb form works similarly: “She reigned as class president for two years” or “That movie reigned at the box office for weeks.”