full moon

noun

"full-moon" is a 8-letter English headword indexed on PlainSpell.

The verdict

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

Unranked
below top-frequency English
9
letters

According to Wiktionary data (CC BY-SA, analyzed September 3, 2026) - The phase of the moon when it is in opposition to the sun and its full disc is therefore visible.

Corpus desk

Index EN-full-moon · full moon · English

full moon · unranked · 0 variants · 0 confusables

  • FREQ-UNRANKED Unranked
  • LEN-LONG 9 letters
  • VOW-3 3 vowels
  • CONFUS-0 No pairs
  • VAR-0 0 variants
  • BOOK-THIN "F" 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 full moon
PropertyValue
Headwordfull moon
LanguageEnglish
Part of speechNoun
Letters9
Misspellings tracked0
Confusable pairs0
SourceWiktionary (kaikki.org)

Long-tail rank of “full moon” in English

full moonfalls outside the top-100,000 ranked English words, the long-tail zone of technical, archaic, or low-frequency vocabulary, exactly where readers second-guess spellings most.

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

Rare enough to double-check

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

full moon doesn't appear in our generated misspelling index, since its letter pattern doesn't lend itself to common typo substitutions. Our dataset records no confusable match here, which usually means its spelling is distinct enough that readers don't reach for a similar-looking word instead.

Etymologically, the entry records: From Middle English ful mone, from Old English full mōna, equivalent to full + moon. The correct English form is full moon, spelled F-U-L-L- -M-O-O-N.

Definition

  1. 1
    The phase of the moon when it is in opposition to the sun and its full disc is therefore visible.
  2. 2
    The moon when it is in opposition to the sun.

Recorded use

Wiktionary example

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

  1. It is true also that the roosters, especially during full moon, crow all night.

Etymology

From Middle English ful mone, from Old English full mōna, equivalent to full + moon.

This word in other languages

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 "full moon"?
"full moon" is spelled F-U-L-L- -M-O-O-N.
What does "full moon" mean?
As a noun, "full moon" means: The phase of the moon when it is in opposition to the sun and its full disc is therefore visible.
What is the origin of the word "full moon"?
From Middle English ful mone, from Old English full mōna, equivalent to full + moon. 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