red letter day

noun

"red-letter-day" is a 12-letter English headword indexed on PlainSpell.

The verdict

“red letter day” is uncommon English (outside the top frequency list), classed as a noun. The kind of spelling people second-guess.

Unranked
below top-frequency English
14
letters

According to Wiktionary data (CC BY-SA, analyzed September 3, 2026) - A day marked in red on calendars; a church feast day.

Corpus desk

Index EN-red-letter-day · red letter day · English

red letter day · unranked · 0 variants · 0 confusables

  • FREQ-UNRANKED Unranked
  • LEN-MEGA 14 letters
  • VOW-5 5 vowels
  • CONFUS-0 No pairs
  • VAR-0 0 variants
  • BOOK-THIN "R" thin
  • PHOTO-UNK Peer pending

Read with this headword: Spelling guide for this pattern

Desk codes from Wiktionary headword shape, FrequencyWords rank tier, confusable-pair count, generated misspelling depth, letter-cohort book size, and photo-finish peer. Not a difficulty grade.

Key facts for red letter day
PropertyValue
Headwordred letter day
LanguageEnglish
Part of speechNoun
Letters14
Misspellings tracked0
Confusable pairs0
SourceWiktionary (kaikki.org)

Long-tail rank of “red letter day” in English

red letter daysits beyond the 100,000 most-frequent English words, in the long tail of technical, archaic, or otherwise rare vocabulary where spelling doubt tends to strike hardest.

Beyond rank #100,000. Source: FrequencyWords open word-frequency list.

Rare enough to double-check

red letter day is uncommon English outside the top frequency list, classed as anoun. Rarity is why readers land here mid-draft. 2 senses are on record.

red letter day doesn't appear in our generated misspelling index, which points to an orthography that plays by predictable English rules. Our confusable-pair dataset has no match for it, which usually means its spelling is distinct enough that readers don't reach for a similar-looking word instead.

Etymologically, the entry records: An allusion to the practice, dating to classical antiquity, of marking important days in red on calendars. The correct English form is red letter day, spelled R-E-D- -L-E-T-T-E-R- -D-A-Y.

Definition

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

Recorded use

Wiktionary examples

These source excerpts show how red letter day appears in context. They illustrate usage; the definition above remains the entry’s reference meaning.

  1. The only red-letter day occurring in July, is the twenty-fifth, called St James's Day.
  2. But the monsters who interrupt men in the middle of a sentence are to be found everywhere; and they are always practising. Red-letter days or black-letter days, festival or fast, makes no difference to them.

Etymology

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

Definitions, pronunciation, and etymology for this entry are drawn from Wiktionary via the kaikki.org structured extract (CC BY-SA). See the methodology for how each field is sourced and updated.

Frequently Asked Questions

How do you spell "red letter day"?
"red letter day" is spelled R-E-D- -L-E-T-T-E-R- -D-A-Y.
What does "red letter day" mean?
As a noun, "red letter day" means: A day marked in red on calendars; a church feast day.
What is the origin of the word "red letter day"?
An allusion to the practice, dating to classical antiquity, of marking important days in red on calendars. See the full etymology section above for more details.
Is PlainSpell free to use?
Yes, PlainSpell is a completely free word reference. You can look up definitions, pronunciations, confusable pairs, homophones, and spelling corrections across 5 languages without any sign-up or subscription.

Source: Wiktionary (via kaikki.org) Structured Wiktionary extract

Source: FrequencyWords open word-frequency list