Definitions

1. noun

the period of most intense or successful activity or achievement of someone or something

“The actress’s heyday was during the 1990s when she starred in a popular TV series.”

2. noun

the period of greatest prosperity or importance of something, such as a country, industry, or region

“The city’s heyday was during the 19th century when it was a major industrial center.”

3. verb

to be at the height of one’s success or popularity

“The singer is said to have been heydaying in the 1980s with her hit single.”