phi
/faɪ/noun
phi is spelled P-H-I: 3 letters and one syllable. It appears 3.5 times per million words in written English, the 13,897th most frequent word form (wordfreq, 2021 data). As a noun, phi means “Φ, the 21st letter of the Euclidean and modern Greek alphabet, usually romanized as "ph"” (English Wiktionary, September 2026). The plural of phi is phis.
How many letters and syllables are in phi?
| Letters | 3: P-H-I |
|---|---|
| Syllables | 1 (from its American pronunciation) |
| In writing | 3.5 times per million words; the 13,897th most frequent word form |
| Wrong spellings searched | none measured in search |
| Sounds like | |
| Same letters |
Sources: letters and syllables from the English Wiktionary's hyphenation or pronunciation and the CMU Pronouncing Dictionary; written frequency: wordfreq 3.1 (a 2021 snapshot of Wikipedia, subtitles, news, books, web text and social media); rhymes and same-letter words are computed by PlainSpell from its own word list.
How common is phi?
Phi appears 3.5 times per million words in written English, the 13,897th most frequent word form in the list.
Source: written frequency: wordfreq 3.1 (a 2021 snapshot of Wikipedia, subtitles, news, books, web text and social media).
How do you pronounce phi?
- /faɪ/
- /fiː/
Phi has one syllable (counted from its American pronunciation in the CMU Pronouncing Dictionary).
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract). Recordings: En-us-phi.ogg, En-us-phi_long_e.ogg, Wikimedia Commons (author and licence on each file's page).
Words people confuse with phi
Sounds like: fie (Wiktionary's homophone list; some hold only in some accents).
Sources: English Wiktionary (homophones, alternative spellings).
What rhymes with phi?
No other word on PlainSpell ends in the same sounds as phi.
Spelled with the same letters in another order: hip.
Computed by PlainSpell from the pronunciations in the English Wiktionary (dump of September 2, 2026): a rhyme shares every sound from the last stressed vowel to the end; ordered by written frequency (wordfreq 3.1).
Forms of phi
- phis plural
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).
What does phi mean?
The meanings the English Wiktionary records, quoted as written there (source below).
noun
- 1
Φ, the 21st letter of the Euclidean and modern Greek alphabet, usually romanized as "ph".
- 2
The golden ratio.
- 3
A visual illusion whereby a sequential pattern of lights produces a false sense of motion.
[…] tolerance (Frenkel-Brunswik 1949) for it showed that those persons with the strongest defences against internal conflict, i.e. obsessionals and conversion hysterics, were those least able to perceive the reality-conflicting phenomenon o
noun
- 1
Initialism of protected health information.
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).
Phi in Spanish, French, German and Portuguese
In the sense Greek letter:
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract). Translations are Wiktionary's, by sense; a linked word has its own PlainSpell page.
Where does phi come from?
From Late Latin phi, from Ancient Greek φεῖ (pheî).
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).