from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. The 19th letter of the Greek alphabet. See Table at alphabet.
  • n. An elementary particle of the lepton family, having a mass about 3,550 times that of the electron, a negative electric charge, and a mean lifetime of 3 × 10-13 seconds. See Table at subatomic particle.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. The name of the letter T/τ in the Greek, Hebrew and ancient Semitic alphabets, being the nineteenth letter of the Classical and Modern Greek, the twentieth letter of Old and Ancient Greek.
  • n. A Τ-shaped sign or structure; a St. Anthony's cross, sometimes considered as a sacred symbol.
  • n. A tau meson, now usually known as a kaon.
  • n. An unstable heavy lepton, which decays into a muon or electron; a tauon.
  • n. A type of protein used to stabilise microtubules.

from the GNU version of the Collaborative International Dictionary of English

  • n. The nineteenth letter (Τ, τ) of the Greek alphabet, equivalent to English t.
  • n. The common American toadfish; -- so called from a marking resembling the Greek letter tau (τ).

from The Century Dictionary and Cyclopedia

  • n. In ichthyology, the toadfish, Batrachus tau.
  • n. In entomology: A beetle.
  • n. A phalænid moth.
  • n. A fly.
  • n. In heraldry, same as tau-cross.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • n. the 19th letter of the Greek alphabet


Greek, of Phoenician origin; see tww in Semitic roots.
(American Heritage® Dictionary of the English Language, Fourth Edition)
From Ancient Greek ταῦ (tau). (Wiktionary)



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