heyday
/ˈheɪdeɪ/noun
(一般作 one's heyday)
- the period of a person's or thing's greatest success, popularity, activity, or vigour（人或物）最成功（受欢迎、活跃或有活力）的时期, 鼎盛时期, 黄金时期：
the paper has lost millions of readers since its heyday in 1964.
这份报纸自1964年它的鼎盛时期以来读者少了几百万。
词源
late 16th cent. (denoting good spirits or passion)： from archaic heyday!, an exclamation of joy, surprise, etc.