Late 16th century, from earlier heyda (1520s), as exclamation – compare hey, hei. Sense “period of success, vigor” is a respelling as heyday based on unrelated day (as “period of time”) – compare day in the sun.
Mellora a túa pronuncia
Practica a expresión oral e a memorización de " heyday " e moitas outras palabras e frases inglés .