the nineteenth letter of the Greek alphabet (Τ, τ)
Origin of tauMiddle English taw, tau (esp. with reference, refer to the tau cross) ; from Classical Latin tau ; from Classical Greek ; from Semitic as in Classical Hebrew (language) tav, tav
The 19th letter of the Greek alphabet. See Table at alphabet.
Origin of tauGreek, of Phoenician origin; see tww in Semitic roots.
- The name of the letter Τ/τ in the Greek, Hebrew and ancient Semitic alphabets, being the nineteenth letter of the Classical and Modern Greek, the twenty-first letter of Old and Ancient Greek.
- A Τ-shaped sign or structure; a St. Anthony's cross, sometimes considered as a sacred symbol.
- 1658: Nor shall we take in the mysticall Tau, or the Crosse of our blessed Saviour, which having in some descriptions an Empedon or crossing foot-stay, made not one single transversion. — Sir Thomas Browne, The Garden of Cyrus (Folio Society 2007, p. 168)
- (physics, dated) A tau meson, now usually known as a kaon.
- (physics) An unstable heavy lepton, which decays into a muon or electron; a tauon.
- (biology) A type of protein used to stabilise microtubules.
- (mathematics, neologism) A constant equal to twice the value of pi; often written τ.
From Ancient Greek ταῦ (tau).