CFS
"cfs" is a 3-letter English headword indexed on PlainSpell.
The verdict
“CFS” is a moderately-common English word, ranked #26,716 in English word frequency and used as a noun.
- #26,716
- frequency rank, English
- 3
- letters
- 20
- confusable pairs
According to Wiktionary data (CC BY-SA, analyzed May 6, 2026) - Initialism of chronic fatigue syndrome.
Visual similarity to commonly confused words
How many letter changes separate each confused pair (Levenshtein distance, normalized).
Source: PlainSpell confusable corpus (Wiktionary, CC BY-SA).
| Property | Value |
|---|---|
| Headword | CFS |
| Language | English |
| Part of speech | Noun |
| Letters | 3 |
| Frequency rank | #26,716 |
| Misspellings tracked | 0 |
| Confusable pairs | 20 |
| Source | Wiktionary (kaikki.org) |
Where “CFS” sits in English frequency
Spelling & Dictionary Insight
The English entry for CFS is 3 letters long, classified as a noun. Corpus data places it at rank #26,716 in overall English word frequency, marking it as uncommon enough that many writers pause before typing it. Wiktionary records 3 distinct senses for this headword, so context determines which meaning a reader should apply.
No generated misspelling entries exist for CFS in our index, and the word's spelling is regular enough that our generator found nothing worth flagging. It also participates in 20 confusable-pair relationships, "co", "CM", "CT", and more, since the words sound or look close enough that writers reach for the wrong one mid-sentence.
Wiktionary doesn't record an etymology for this headword, so its spelling pattern is best understood through pronunciation rather than a traceable origin. The correct English form is CFS, spelled C-F-S.
Definition
- 1Initialism of chronic fatigue syndrome.
- 2Initialism of cramp fasciculation syndrome.
- 3Initialism of Canada Flight Supplement (a pilot's guide to aerodromes, air control zones, and airways in Canadian airspace and Canadian air traffic control zones).
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
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Using “CFS”
The practical upshot for anyone who landed here from a spell-check.
- The one correct English spelling is C-F-S - every other letter order is a misspelling in standard orthography.
- Don't mix it up with “co” - see the side-by-side comparison. CFS vs co
- 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.