CSI
"csi" is a 3-letter English headword indexed on PlainSpell.
The verdict
“CSI” is a moderately-common English word, ranked #20,894 in English word frequency and used as a noun.
- #20,894
- frequency rank, English
- 3
- letters
- 20
- confusable pairs
According to Wiktionary data (CC BY-SA, analyzed May 6, 2026) - Initialism of crime scene investigation (a term of forensic science).
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 | CSI |
| Language | English |
| Part of speech | Noun |
| Letters | 3 |
| Frequency rank | #20,894 |
| Misspellings tracked | 0 |
| Confusable pairs | 20 |
| Source | Wiktionary (kaikki.org) |
Where “CSI” sits in English frequency
Spelling & Dictionary Insight
The English entry for CSI is 3 letters long, classified as a noun. Corpus data places it at rank #20,894 in overall English word frequency, marking it as uncommon enough that many writers pause before typing it. Wiktionary records 5 distinct senses for this headword, so context determines which meaning a reader should apply.
No misspelling variants are generated for CSI in our index, suggesting the orthography follows predictable English patterns. It also participates in 20 confusable-pair relationships, "CT", "CV", "CU", and more, a pairing that trips writers up because the two words share enough sound or shape to blur together.
Wiktionary doesn't record an etymology for this headword, so spelling patterns must be inferred from the word's phoneme-to-grapheme mapping rather than from a documented borrowing chain. The correct English form is CSI, spelled C-S-I.
Definition
- 1Initialism of crime scene investigation (a term of forensic science).
- 2Initialism of crime scene investigator.
- 3Initialism of Customer Satisfaction Index.
- 4Initialism of Companion of the Order of the Star of India.
- 5Initialism of consumer safety inspector.
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); 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 “CSI”
The practical upshot for anyone who landed here from a spell-check.
- The one correct English spelling is C-S-I - every other letter order is a misspelling in standard orthography.
- Don't mix it up with “CT” - see the side-by-side comparison. CSI vs CT
- 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.