heyday
n.the period of time when someone or something is most successful, popular, or powerful. You use this to talk about the 'golden age' of a person's career or a specific era.
n.the period of greatest success, popularity, or vigour. Often used to describe the peak of a historical era, a career, or a specific technology.
“In its heyday, the city was a major center for trade.”
“During the heyday of silent film, actors relied entirely on physical expression to convey emotion.”
“The crumbling ruins serve as a stark reminder of the empire's former glory during its 12th-century heyday, when its influence stretched across three continents.”
Usually used in the singular, often following the preposition 'in' ('in its heyday').
“His anecdotes are punctuated with nervous laughter, although he's better at making eye contact than when we first met in the Killers' heyday.”
“Sharks started to inflate to mega body sizes during the heyday of the dinosaurs.”
Late 16th century, from earlier heyda (1520s), as exclamation – compare hey, hei. Sense “period of success, vigor” is a respelling as heyday based on unrelated day (as “period of time”) – compare day in the sun.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.