tau
/taʊ/
"tau" is a 3-letter English headword indexed on PlainSpell.
The verdict
“tau” sits in 20 confusable pairs (corpus #19,983) as a noun. The look-alike neighbours are the real trap.
- #19,983
- frequency rank, English
- 3,151
- “T” headwords
- 20
- confusable pairs
According to Wiktionary data (CC BY-SA, analyzed September 3, 2026) - The letter Τ /τ in the Greek alphabet; being the nineteenth letter of the Classical and Modern Greek, and the twenty-first letter of the Old and Ancient Greek alphabets.
Corpus desk
Index EN-tau · tau · English
tau · rank #19,983 · 0 variants · 20 confusables
- FREQ-MID #19,983
- LEN-MID 3 letters
- VOW-2 2 vowels
- CONFUS-HIGH 20 pairs
- VAR-0 0 variants
- BOOK-MID 3,151
- PHOTO-FINISH Sykes
Nearest frequency peer: Sykes (-1 rank slots)
Read with this headword: Spelling guide for this pattern
Desk codes from Wiktionary headword shape, FrequencyWords rank tier, confusable-pair count, generated misspelling depth, letter-cohort book size, and photo-finish peer. Not a difficulty grade.
Frequency neighbours of confusable “tau”
Peers at similar corpus weight, separate from look-alike pairs below
- Sudanese
Sudanese
80,021 corpus weight
- sunscreen
sunscreen
80,020 corpus weight
- Sykes
Sykes
80,019 corpus weight
- tau
tau
80,018 corpus weight
- tempest
tempest
80,017 corpus weight
- tending
tending
80,016 corpus weight
What this shows Bars place “tau” against nearest ranked English headwords, not a reprint of the confusable-pair desk.
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 | tau |
| Language | English |
| Part of speech | Noun |
| IPA | /taʊ/ |
| Letters | 3 |
| Frequency rank | #19,983 |
| Misspellings tracked | 0 |
| Confusable pairs | 20 |
| Source | Wiktionary (kaikki.org) |
Corpus rank beside confusables of “tau”
Easy to mix with look-alikes
The spelling risk for tau is neighbouring look-alikes ("to", "TV", …), not just typos; it is anoun pronounced /taʊ/. Frequency #19,983 among 3,151 “T” headwords. 11 recorded senses keep meaning in play.
Our edit-distance generator produced no likely misspellings for tau, a straightforward case of a spelling with little room for common typos. It also participates in 20 confusable-pair relationships, "to", "TV", "te", and more, since the words sound or look close enough that writers reach for the wrong one mid-sentence.
Etymologically, the entry records: From Middle English tau, taue, from Latin tau, from Ancient Greek ταῦ (taû) and Hebrew תָּו (tav). Sense 7 was used by Joseph M. Lindenberg in 1991, and popularized by the American educator and entrepreneur Michael Hartl in a 2010 paper which explains that … The correct English form is tau, spelled T-A-U.
Definition
- 1The letter Τ /τ in the Greek alphabet; being the nineteenth letter of the Classical and Modern Greek, and the twenty-first letter of the Old and Ancient Greek alphabets.
- 2Alternative form of taw; the 22nd and last letter of many Semitic alphabets/abjads, including Phoenician, Aramaic, Hebrew, Syriac, and Arabic.
- 3A Τ-shaped object or sign; a Saint Anthony's cross, sometimes regarded as a sacred symbol.
- 4A Τ-shaped object or sign; a Saint Anthony's cross, sometimes regarded as a sacred symbol.
- 5The ankh symbol (☥).
- 6Chiefly written τ: used to designate the nineteenth star (usually according to brightness) in a constellation.
- 7A measurement of the sensitivity of the value of an option to changes in the implied volatility of the price of the underlying asset.
- 8Chiefly written τ: an irrational and transcendental constant representing the ratio of the circumference of a Euclidean circle to its radius, equal to twice the value of pi (2π; approximately 6.2831853071).
- 9Ellipsis of tau protein (“a protein abundant especially in the neurons of the human central nervous system that stabilizes microtubules, and when misfolded is associated with forms of dementia such as Alzheimer's and Parkinson's diseases”).
- 10Chiefly written τ.
- 11Chiefly written τ.
Recorded use
Wiktionary examplesThese source excerpts show how tau appears in context. They illustrate usage; the definition above remains the entry’s reference meaning.
Hence it appears that the spits, or skewers, on which and to which the lamb was fixed and fastened in order to be roasted, assumed the form of a cross, not such a tau-cross as is engraved in Dr. Oliver’s Historical Landmarks of Freemasonry, vol. i. p. 80. having three arms only like the Greek letter tau; but a cross like the ancient Hebrew tau, with four…
In the Spanish translation of Sallust, by the Infant Don Gabriel in 1772, called the Infant Sallust, there is a curious dissertation by Father Perez Bayer on the resemblance between the ancient Hebrew and Phœnician alphabets, in which it is observed that the Hebrew Tau was written in pure Phœnician, […]
Etymology
From Middle English tau, taue, from Latin tau, from Ancient Greek ταῦ (taû) and Hebrew תָּו (tav). Sense 7 was used by Joseph M. Lindenberg in 1991, and popularized by the American educator and entrepreneur Michael Hartl in a 2010 paper which explains that τ resembles π; and that τ is the Greek equivalent of t, the first letter of turn, and 2π corresponds to one turn of a circle with a radius of one unit. Sense 8.1 (“ellipsis of tau lepton or tau particle”) was coined by the American physicist Martin Lewis Perl (1927–2014) after the first letter of Ancient Greek τρίτον (tríton, “third”), since the tau lepton or tauon was the third charged lepton discovered.
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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Similar English words by spelling shape
Same letter count and similar misspelling depth for "tau", not the corpus desk frequency band.
Same letter count
Frequency-ranked English headwords with 3 letters (nearest by frequency rank).