HAYDAY has nothing to do with the dried grass our horses love to eat. In fact, HAYDAY is a misspelling of the word HEYDAY. Please don’t fret if you have mistakenly used HAYDAY, it’s a common error with an impressive history – we’ve been misspelling it for over 200 years
HEYDAY first appeared in 16th century English as a noun meaning “high spirits”. In Shakespeare’s Hamlet, Prince of Denmark tells his mother, “You cannot call it love; for at your age/The heyday in the blood is tame….”
In the 18th century the meaning of “day” shifted to mean a period of time bringing us to HEYDAY’s current meaning “the peak of success”. For example, “In his heyday, no other horse could beat Secretariat”.
Here is a simple mnemonic to help you remember to use HEYDAY.
“Hay is for horses, not for this word”