Fermat number
Detailed reference entry for the English word "fermat-number", 13-letters, with pronunciation in International Phonetic Alphabet notation, etymology traced through Germanic and Romance roots where applicable, common misspelling variants catalogued from Wiktionary, and usage frequency ranked against an open word-frequency list covering the top 100,000 English words. PlainSpell covers English, Spanish, Portuguese, French, and German spelling with confusable-pair detection that highlights visually and phonetically similar words. This entry for "fermat-number" includes synonyms, antonyms, homophones, and cross-language translation pointers sourced from Wiktionary via the kaikki.org extract. Whether you are verifying the correct spelling of "fermat-number" for academic writing, checking homophone confusion, or exploring etymological origins, this page provides a citation-backed, free reference that requires no sign-up.
The verdict
“Fermat number” is outside the top-ranked English vocabulary, used as a noun - the kind of word writers most often double-check.
- Unranked
- below top-frequency English
- 13
- letters
According to Wiktionary data (CC BY-SA, analyzed May 6, 2026) - An integer which is one more than two raised to a power which is itself a power of two (i.e., is expressible in the form 2^(2ⁿ)+1 for some n>0); equivalently, a number that is one more than two rai...
Compare similar words
See how Fermat number compares against similar English words.
Browse all word comparisons →| Property | Value |
|---|---|
| Headword | Fermat number |
| Language | English |
| Part of speech | Noun |
| Letters | 13 |
| Misspellings tracked | 0 |
| Confusable pairs | 0 |
| Source | Wiktionary (kaikki.org) |
Where “Fermat number” sits in English frequency
Spelling & Dictionary Insight
The English entry for Fermat number is 13 letters long, classified as a noun. It sits outside the most-frequent rank tiers, which is often why uncommon words generate more spelling variants per reader. The dominant gloss from Wiktionary reads: "An integer which is one more than two raised to a power which is itself a power of two (i.e., is expressible in the form 2^(2ⁿ)+1 for some n>0); equivalently, a number that is one more than two rai...".
No misspelling variants are generated for Fermat number in our index, suggesting the orthography follows predictable English patterns. It is not paired with a close-neighbour confusable in our dataset, which tends to mean the word is visually distinctive enough to stand on its own.
Etymologically, the entry records: Named after French lawyer and amateur mathematician Pierre de Fermat (1601–1665). Root origin matters for spelling because borrowed morphemes (Greek, Latin, Old French, Old English) carry their source-language orthographic conventions into modern English, which is why historical etymology is often the cleanest predictor of whether a cluster like "-ough", "-eau", or "-tion" will appear. For readers arriving here from a spelling check, the authoritative guidance is: the correct English form is Fermat number, spelled F-E-R-M-A-T- -N-U-M-B-E-R, and any other sequence of those letters, regardless of how natural it feels, is a misspelling in standard orthography.
Definition
- 1An integer which is one more than two raised to a power which is itself a power of two (i.e., is expressible in the form 2^(2ⁿ)+1 for some n>0); equivalently, a number that is one more than two raised to some power (is expressible as 2ⁿ+1) and is prime.
Etymology
Named after French lawyer and amateur mathematician Pierre de Fermat (1601–1665).
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.
Cite this page
Free to reuse with attribution (CC BY-SA). Copy the citation:
PlainSpell, “Fermat number, English word data” (May 6, 2026). Derived from Wiktionary (kaikki.org, CC BY-SA) and an open word-frequency list. https://plainspell.com/en/word/fermat-number
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Using “Fermat number”
The practical upshot for anyone who landed here from a spell-check.
- The one correct English spelling is F-E-R-M-A-T- -N-U-M-B-E-R - every other letter order is a misspelling in standard orthography.
- Browse more English words and confusable pairs in the same reference. English words
Nearby English words
Other entries that begin with the letter F in our English index: