Heyday comes from the old Germanic word "heida" meaning "hurrah!" In its earliest appearances in English, in the 16th century, "heyday" was used as an interjection that expressed elation or wonder (similar to the English word hey, from which it derives).
What is the synonym of heyday?
noun. 1'the paper has lost millions of readers since its heyday in 1964' prime, peak, height, high point, high spot, peak of perfection, pinnacle, acme, zenith, day, time, bloom, flowering, culmination, crowning point. prime of life, best days, best years, salad days.