fastness

/ˈfɑːs(t)nəs/

//ˈfɑːs(t)nəs// noun

By · According to Wiktionary data (CC BY-SA) ·

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

The verdict

“fastness” is uncommon English (frequency #89,348 among 2,507 “F” headwords), classed as a noun. The kind of spelling people second-guess.

#89,348
frequency rank, English
2,507
“F” headwords

According to Wiktionary data (CC BY-SA, analyzed September 3, 2026) - The quality or state of being fast (in various senses).

Corpus desk

Index EN-fastness · fastness · English

fastness · rank #89,348 · 0 variants · 0 confusables

  • FREQ-RARE #89,348
  • LEN-LONG 8 letters
  • VOW-2 2 vowels
  • CONFUS-0 No pairs
  • VAR-0 0 variants
  • BOOK-MID 2,507
  • PHOTO-FINISH Fedorov

Nearest frequency peer: Fedorov (+1 rank slots)

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.

Long-tail ranks near “fastness”

Sparse band: bars invert rank so rarer forms read shorter

corpus weight

What this shows Long-tail view: where “fastness” sits against similarly uncommon English ranks.

Source FrequencyWords open word-frequency list As of September 3, 2026
Key facts for fastness
PropertyValue
Headwordfastness
LanguageEnglish
Part of speechNoun
IPA/ˈfɑːs(t)nəs/
Letters8
Frequency rank#89,348
Misspellings tracked0
Confusable pairs0
SourceWiktionary (kaikki.org)

Long-tail rank of “fastness” in English

This scale runs from the tiny cluster of words that carry ordinary speech (left) to the long tail of words almost nobody reaches for (right).fastnessfalls in this rarity band:

#1#100#1K#10K#100K
← used constantlyrarely used →

Ticks step logarithmically, so each one marks a roughly tenfold drop in how often the word turns up. Rare peers in the same band: “Fedorov” (#89,349), “Feeny” (#89,350), “feigns” (#89,352). Among 2,507 “F” headwords, “fastness” is #89,348. Source: FrequencyWords open word-frequency list.

Rare enough to double-check

fastness is uncommon English at frequency #89,348 among 2,507 “F” headwords, classed as anoun, transcribed /ˈfɑːs(t)nəs/. Rarity is why readers land here mid-draft. 8 senses are on record.

fastness has no tracked misspelling variants, typically a sign the spelling maps closely to how the word sounds. This entry stands alone in our confusable dataset, a sign it's visually distinctive enough not to be mixed up with another word.

Etymologically, the entry records: From Middle English fastnes, fastnesse (“immovableness, stability; firmness, solidness; secure attachment; constancy; obstinacy; something giving firmness or strength; of sleep: soundness; of a wound: healing; assurance, confirmation”) [and other forms], fr… The correct English form is fastness, spelled F-A-S-T-N-E-S-S.

Definition

  1. 1
    The quality or state of being fast (in various senses).
  2. 2
    The quality or state of being fast (in various senses).
  3. 3
    The quality or state of being fast (in various senses).
  4. 4
    The quality or state of being fast (in various senses).
  5. 5
    The quality or state of being fast (in various senses).
  6. 6
    The quality or state of being fast (in various senses).
  7. 7
    Something that is fast, or that causes someone or something to be fast (in various senses).
  8. 8
    Something that is fast, or that causes someone or something to be fast (in various senses).

Recorded use

Wiktionary examples

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

  1. [T]he thing, as it is, having firſt taken vp her ſtand in the memory, and there by the way of knowledge and witting, imprinted it-ſelfe, it were hard it ſhould not repreſent it ſelfe to the imagination, diſplacing and ſupplanting falſehood, which therein can have no ſuch footing, or ſetled faſtneſſe: […]
  2. [T]his is the ſure, infallible Teſt of Love, that the Meaſure of its Strength is to be taken by the Faſtneſs of its Hold.

Etymology

From Middle English fastnes, fastnesse (“immovableness, stability; firmness, solidness; secure attachment; constancy; obstinacy; something giving firmness or strength; of sleep: soundness; of a wound: healing; assurance, confirmation”) [and other forms], from Old English fæstnes (“fastness, firmness, stability; resolution; tenacity; vigour; firmament; fortification”) [and other forms], from fæst (“firm, stable; constant”) (from Proto-Germanic *fastuz (“firm, fixed; secure”); see further at that entry) + -nes (suffix forming abstract nouns denoting a quality or state). The English word may be analysed as fast + -ness.

This word in other languages

Feste(Deutsch)

Definitions, pronunciation, and etymology for this entry are drawn from Wiktionary via the kaikki.org structured extract (CC BY-SA); frequency ordering uses the FrequencyWords open word-frequency list (2018 English corpus, MIT). See the methodology for how each field is sourced and updated.

Frequently Asked Questions

How do you spell "fastness"?
"fastness" is spelled F-A-S-T-N-E-S-S. The IPA pronunciation is /ˈfɑːs(t)nəs/.
What does "fastness" mean?
As a noun, "fastness" means: The quality or state of being fast (in various senses).
How do you pronounce "fastness"?
The IPA (International Phonetic Alphabet) transcription for "fastness" is /ˈfɑːs(t)nəs/. 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 "fastness"?
From Middle English fastnes, fastnesse (“immovableness, stability; firmness, solidness; secure attachment; constancy; obstinacy; something giving firmness or strength; of sleep: soundness; of a wound: healing; assurance, confirmation”) [and other ... 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.

Similar English words by spelling shape

Same letter count and similar misspelling depth for "fastness", not the corpus desk frequency band.

Same letter count

Frequency-ranked English headwords with 8 letters (nearest by frequency rank).

facially#89,343ethicist#89,337entropic#89,333dreamily#89,312

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

Source: FrequencyWords open word-frequency list