n. [ Prob. for. high day. See High, and Day. ] The time of triumph and exultation; hence, joy, high spirits, frolicsomeness; wildness. [ 1913 Webster ]
The heyday in the blood is tame. Shak. [ 1913 Webster ]
In the heyday of their victories. J. H. Newman. [ 1913 Webster ]
interj. [ Cf. G. heida, or hei da, D. hei daar. Cf. Hey, and There. ] An expression of frolic and exultation, and sometimes of wonder. B. Jonson. [ 1913 Webster ]