red-letter day

1. 1.

   a memorably happy or noteworthy day (from the custom of marking holy days in red on church calendars)

   Broaderday

Questions about red-letter day

What does red-letter day mean?

red-letter day means "a memorably happy or noteworthy day (from the custom of marking holy days in red on church calendars)".

Is red-letter day a common word?

red-letter day is banded "Rare" — specialist or archaic — most readers will not have met it. The band comes from how often the word appears in a large corpus of everyday English, not from an editor's impression.