pi
/paɪ/
"pi" is a 2-letter English headword indexed on PlainSpell.
The verdict
“pi” is a regularly-used English word, ranked #8,073 in English word frequency and used as a noun.
- #8,073
- frequency rank, English
- 2
- letters
- 20
- confusable pairs
According to Wiktionary data (CC BY-SA, analyzed May 6, 2026) - The sixteenth letter of the Classical and Modern Greek alphabets and the seventeenth in Old Greek.
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 | pi |
| Language | English |
| Part of speech | Noun |
| IPA | /paɪ/ |
| Letters | 2 |
| Frequency rank | #8,073 |
| Misspellings tracked | 0 |
| Confusable pairs | 20 |
| Source | Wiktionary (kaikki.org) |
Where “pi” sits in English frequency
Spelling & Dictionary Insight
The English entry for pi is 2 letters long, classified as a noun, and transcribed in the International Phonetic Alphabet as /paɪ/. Corpus data places it at rank #8,073 in overall English word frequency, indicating it appears regularly in written and spoken text. Wiktionary records 2 distinct senses for this headword, so context determines which meaning a reader should apply.
pi doesn't appear in our generated misspelling index, a straightforward case of a spelling with little room for common typos. It also participates in 20 confusable-pair relationships, "PM", "PP", "PR", and more, where similar look or sound leads writers to substitute one word for another in context.
Etymologically, the entry records: From Koine Greek πῖ (pî), from Ancient Greek πεῖ (peî), ultimately from Proto-Semitic *pay- (“mouth”). Doublet of pe. Its mathematical use apparently stems from its use as the first letter in περιφέρεια (periphéreia, “periphery; circumference”) and was firs… The correct English form is pi, spelled P-I.
Definition
- 1The sixteenth letter of the Classical and Modern Greek alphabets and the seventeenth in Old Greek.
- 2An irrational and transcendental constant representing the ratio of the circumference of a Euclidean circle to its diameter; approximately 3.14159265358979323846264338327950; usually written π.
Etymology
From Koine Greek πῖ (pî), from Ancient Greek πεῖ (peî), ultimately from Proto-Semitic *pay- (“mouth”). Doublet of pe. Its mathematical use apparently stems from its use as the first letter in περιφέρεια (periphéreia, “periphery; circumference”) and was first cited in 1706 in the Synopsis Palmariorum Matheseos by William Jones.
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 “pi”
The practical upshot for anyone who landed here from a spell-check.
- The one correct English spelling is P-I - every other letter order is a misspelling in standard orthography.
- Say it as /paɪ/ (IPA); tap the speaker on the pronunciation badge to hear it where audio exists.
- Don't mix it up with “PM” - see the side-by-side comparison. pi vs PM
- 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.