1. the period of greatest success, popularity, or power; prime time
Usage: usually singular; often used with 'in one's' or 'in the'

Examples

• The 1960s were the heyday of rock and roll.
• In her heyday, she was the most famous actress in Hollywood.
• The company experienced its heyday during the early 2000s before the market crash.
• That restaurant was popular in its heyday, but it has lost customers over the years.
• The heyday of silent films ended with the arrival of sound technology.
• He reminisced about the heyday of his youth when he was an athlete.
• The British Empire reached its heyday in the nineteenth century.