red-letter

[ red-let-er ]

adjective

1. marked by red letters, as festival days in the church calendar.
2. memorable; especially important or happy:

   a red-letter day in his life.

3. (of a Bible) having the quoted words of Jesus appear in red type:

   a red-letter edition;

   the red-letter New Testament presented at her baptism.

Word History and Origins

Origin of red-letter¹

First recorded in 1660–70

Example Sentences

Turns out, after all, to be a red-letter day or, that is, a brown-liquid evening.

From The Daily Beast

Our run from Hereford up the Wye Valley to the sea, we agreed was one of our red-letter days.

From Project Gutenberg

But the longest red-letter day has its ending, and time and tide beckon one with the brutality of an impatient jailer.

From Project Gutenberg

Phœbe's graduation from the Greenwald High School was her red-letter day.

From Project Gutenberg

However that may be, certain it is that this is a red-letter night at the Mermaid.

From Project Gutenberg

The morning when were produced these charming little miracles remains a red-letter day in our household.

From Project Gutenberg