FSB
"fsb" is a 3-letter English headword indexed on PlainSpell.
The verdict
“FSB” is a moderately-common English word, ranked #32,815 in English word frequency and used as a proper noun.
- #32,815
- frequency rank, English
- 3
- letters
- 20
- confusable pairs
According to Wiktionary data (CC BY-SA, analyzed May 6, 2026) - The Federal Security Service of the Russian Federation.
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 | FSB |
| Language | English |
| Part of speech | Proper noun |
| Letters | 3 |
| Frequency rank | #32,815 |
| Misspellings tracked | 0 |
| Confusable pairs | 20 |
| Source | Wiktionary (kaikki.org) |
Where “FSB” sits in English frequency
Spelling & Dictionary Insight
The English entry for FSB is 3 letters long, classified as a proper noun. Corpus data places it at rank #32,815 in overall English word frequency, marking it as uncommon enough that many writers pause before typing it. The dominant gloss from Wiktionary reads: "The Federal Security Service of the Russian Federation.".
No misspelling variants are generated for FSB in our index, a straightforward case of a spelling with little room for common typos. It also participates in 20 confusable-pair relationships, "fu", "FW", "fy", and more, where similar look or sound leads writers to substitute one word for another in context.
Etymologically, the entry records: From Russian ФСБ (FSB), initialism of Федеральная Служба Безопасности (Federalʹnaja Služba Bezopasnosti, “Federal Security Service”). The correct English form is FSB, spelled F-S-B.
Definition
- 1The Federal Security Service of the Russian Federation.
Etymology
From Russian ФСБ (FSB), initialism of Федеральная Служба Безопасности (Federalʹnaja Služba Bezopasnosti, “Federal Security Service”).
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 “FSB”
The practical upshot for anyone who landed here from a spell-check.
- The one correct English spelling is F-S-B - every other letter order is a misspelling in standard orthography.
- Don't mix it up with “fu” - see the side-by-side comparison. FSB vs fu
- 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.