heyday /ˈheɪdeɪ/exclamation 2noun 2forms 1 exclamation2 •A lively greeting."Heyday, Miss Morland!" said he. "What is the meaning of this? I thought you and I were to dance together." — 1798 •(no longer used) An expression of frolic and exultation, and sometimes of wonder."Come follow me, my wags, and say, as I say. There's no riches but in rags; hey day, hey day, &c." — 1600 noun2 •A period of success, popularity, or power; prime.The early twentieth century was the heyday of the steam locomotive. •(no longer used) An exultation of the spirits; gaiety; frolic. formsheydays
