Is “Heyday” a Scrabble word?
Yes
HEYDAY
Valid in at least one Scrabble dictionary
Valid in these dictionaries
SOWPODS / CSW
Scrabble UK & International
TWL / NWL
Scrabble North America
Large English Dictionary
General English word list
Meaning of Heyday
/ˈheɪdeɪ/
noun
1.A period of success, popularity, or power; prime.
“The early twentieth century was the heyday of the steam locomotive.”
2.An exultation of the spirits; gaiety; frolic.
Synonyms: day in the sun, golden age, golden years
interjection
1.A lively greeting.
2.An expression of frolic and exultation, and sometimes of wonder.