blue hour

/ˈbluː aʊə/

//ˈbluː aʊə// noun

"blue-hour" is a 8-letter English headword indexed on PlainSpell.

The verdict

“blue hour” 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 May 6, 2026) - The period of twilight when the Sun is approximately 4-8° below the horizon and the sky is within a range of blue colors.

Key facts for blue hour
PropertyValue
Headwordblue hour
LanguageEnglish
Part of speechNoun
IPA/ˈbluː aʊə/
Letters9
Misspellings tracked0
Confusable pairs0
SourceWiktionary (kaikki.org)

Where “blue hour” sits in English frequency

blue hour falls 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

blue hour is uncommon English outside the top frequency list, classed as anoun, transcribed /ˈbluː aʊə/. Rarity is why readers land here mid-draft. Gloss: "The period of twilight when the Sun is approximately 4-8° below the horizon and the sky is within a range of blue colors.".

Zero misspellings are on record for blue hour in our index, typically a sign the spelling maps closely to how the word sounds. No confusable counterpart is on file for this word, which usually means its spelling is distinct enough that readers don't reach for a similar-looking word instead.

Etymologically, the entry records: Calque of French heure bleue. The correct English form is blue hour, spelled B-L-U-E- -H-O-U-R.

Definition

  1. 1
    The period of twilight when the Sun is approximately 4-8° below the horizon and the sky is within a range of blue colors.

Etymology

Calque of French heure bleue.

Synonyms

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 "blue hour"?
"blue hour" is spelled B-L-U-E- -H-O-U-R. The IPA pronunciation is /ˈbluː aʊə/.
What does "blue hour" mean?
As a noun, "blue hour" means: The period of twilight when the Sun is approximately 4-8° below the horizon and the sky is within a range of blue colors.
How do you pronounce "blue hour"?
The IPA (International Phonetic Alphabet) transcription for "blue hour" is /ˈbluː aʊə/. Click the speaker icon on the pronunciation badge above to hear it spoken aloud where audio is available.
What is the origin of the word "blue hour"?
Calque of French heure bleue. 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.

Using “blue hour”

The practical upshot for anyone who landed here from a spell-check.

  • The one correct English spelling is B-L-U-E- -H-O-U-R - every other letter order is a misspelling in standard orthography.
  • Say it as /ˈbluː aʊə/ (IPA); tap the speaker on the pronunciation badge to hear it where audio exists.
  • Browse more English words and confusable pairs in the same reference. English words
Data Source

Wiktionary (via kaikki.org), licensed under CC BY-SA & GFDL. Word ordering uses an open word-frequency list; misspelling variants are generated by edit-distance from the correct headword.

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

Source: FrequencyWords open word-frequency list