to rule a nation or group of nations as their king, queen, or emperor:
George VI reigned from 1936 to 1952.
Pharaohs reigned over Egypt for centuries.
if a feeling or quality reigns, it exists strongly for a period of time:
For several minutes confusion reigned.
Silence reigned while we waited for news.
the most recent winner of a competition:
Can he defeat the reigning Wimbledon champion?
if someone or something reigns supreme, they are the most important part of a situation or time:
It was a time when romance reigned supreme.