red letter day
Definition from Wiktionary, the free dictionary
From the practice of marking feast-days in red on church calendars.
- (idiomatic) A particularly significant day or a day to celebrate (personal or sectarian).
- Monday was a red letter day for her. She accomplished a lot and had fun doing it.
- We saw losses for the days in a row, but Black Tuesday was the worst red letter day of them all.
- 1975, John Ankenbruck, Twentieth Century History of Fort Wayne - Page 286
- "In the meantime, the St. Valentine's Day Massacre at Chicago was a red-letter day in the gangster wars."
- Usually used to refer to a notably positive, favorable occasion, but sometimes used with a negative sense.