A reign is a period when someone has control or authority over a country or organization. It can also refer to the time during which something is popular or widely accepted.
When we talk about a monarch's reign, it usually means how long they were the king or queen of their country. For example, "Queen Elizabeth II had a 69-year reign," so you know exactly when she was in power. This usage of the word "reign" is often used to describe the length of time someone held an official title.
But "reign" can also be used for something that's popular or trendy for a certain period. If a new fashion trend has a long reign, it means it's been around and in style for many years.
The exercise of sovereign power.
Example: England prospered under Elizabeth I's reign.
