# red letter day

> English word · Noun

## Definitions
1. A day marked in red on calendars; a church feast day.
2. A particularly significant day; a day of personal or sectarian celebration.

## Etymology
An allusion to the practice, dating to classical antiquity, of marking important days in red on calendars.

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-09-03.
Canonical page: https://plainspell.com/en/word/red-letter-day