/'heɪdeɪ; `he,de/
n [sing] time of greatest success, prosperity, power, etc 最成功、最繁荣、最强盛等的时期
*She was a great singer in her heyday. 她在自己的黄金时代是个了不起的歌唱家.
* Steam railways had their heyday in the 19th century. 19世纪是蒸汽机车的全盛时期.

n [C usually singular]
[Date: 1500-1600; Origin: heyda a shout of happiness (16-17 centuries); influenced by day]
the time when someone or something was most popular, successful, or powerful
in sb's heyday
　a picture of Greta Garbo in her heyday