red-letter day

British  

noun

1. a memorably important or happy occasion

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red-letter day Cultural  

1. A special or memorable day; the expression refers to the old custom of printing holidays in red on calendars: “John got promoted and engaged to be married yesterday; it was truly a red-letter day for him.”

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red-letter day Idioms  

1. A special occasion, as in When Jack comes home from his tour of duty, that'll be a red-letter day. This term alludes to the practice of marking feast days and other holy days in red on church calendars, dating from the 1400s. [c. 1700]

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Etymology

Origin of red-letter day

C18: from the red letters used in ecclesiastical calendars to indicate saints' days and feasts

Example Sentences

This was a red-letter day for Adelaide-born Head as he scored a stunning century in front of a packed crowd on familiar territory.

From BBC

This was a red-letter day in the history of Liverpool's famous old stadium as the new top deck of the Anfield Road Stand was in use for the first time.

From BBC

His 24 points - his highest tally in a Test match - included two tries, but his kicking, vision and communicative skills laid the foundation for Ireland's red-letter day.

From BBC

Saturday was a red-letter day for the history of art in Southern California.

From Los Angeles Times

It was a red-letter day for Elizebeth, proof that she had lived up to her old dreams of achievement.

From Literature