Late 16th century, from earlierheyda (1520s), as exclamation – comparehey,hei. Sense “period of success, vigor” is a respelling asheyday based on unrelatedday (as “period of time”) – compareday in the sun.[1]
Must your hot ytch and plurisie of lust, Theheyday of your luxury, be fedd Up to a surfeite, and could none but I Be pickt out to be cloake to your close tricks, Your belly-sports?
Here Jones, having ordered a servant to show a room above stairs, was ascending, when the dishevelled fair, hastily following, was laid hold on by the master of the house, who cried, “Heyday, where is that beggar wench going? Stay below stairs, I desire you.”
