standard deviation
"standard-deviation" is a 17-letter English headword indexed on PlainSpell.
The verdict
“standard deviation” is uncommon English (outside the top frequency list), classed as a noun. The kind of spelling people second-guess.
- Unranked
- below top-frequency English
- 18
- letters
According to Wiktionary data (CC BY-SA, analyzed May 6, 2026) - A measure of how spread out data values are around the mean, defined as the square root of the variance. Represented with the Greek letter σ (sigma).
| Property | Value |
|---|---|
| Headword | standard deviation |
| Language | English |
| Part of speech | Noun |
| Letters | 18 |
| Misspellings tracked | 0 |
| Confusable pairs | 0 |
| Source | Wiktionary (kaikki.org) |
Where “standard deviation” sits in English frequency
Rare enough to double-check
standard deviation is uncommon English outside the top frequency list, classed as anoun. Rarity is why readers land here mid-draft. Gloss: "A measure of how spread out data values are around the mean, defined as the square root of the variance. Represented with the Greek letter σ (sigma).".
No misspelling variants are generated for standard deviation in our index, which points to an orthography that plays by predictable English rules. Our confusable-pair dataset has no match for it, a sign it's visually distinctive enough not to be mixed up with another word.
Etymologically, the entry records: Coined by English mathematician, biometrician, and eugenicist Karl Pearson in 1894 in his paper "On the dissection of asymmetrical frequency curves". The correct English form is standard deviation, spelled S-T-A-N-D-A-R-D- -D-E-V-I-A-T-I-O-N.
Definition
- 1A measure of how spread out data values are around the mean, defined as the square root of the variance. Represented with the Greek letter σ (sigma).
Etymology
Coined by English mathematician, biometrician, and eugenicist Karl Pearson in 1894 in his paper "On the dissection of asymmetrical frequency curves".
Synonyms
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). See the methodology for how each field is sourced and updated.
Frequently Asked Questions
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Using “standard deviation”
The practical upshot for anyone who landed here from a spell-check.
- The one correct English spelling is S-T-A-N-D-A-R-D- -D-E-V-I-A-T-I-O-N - every other letter order is a misspelling in standard orthography.
- 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.