[ tou, taw for 1, 2, 4; tahv, tawv for 3 ]
/ taʊ, tɔ for 1, 2, 4; tɑv, tɔv for 3 /


the 19th letter of the Greek alphabet (T, τ).
the consonant sound represented by this letter.
Also tau·on [tou-on] /ˈtaʊ ɒn/. Physics. tau lepton.
Also called tau protein. Biochemistry. a protein that is an important component of nerve cells, helping to maintain their function and structure: in the brain, distortions in the protein’s molecular shape is associated with the onset of Alzheimer’s disease.

Origin of tau

1250–1300; Middle English < Latin < Greek taû < Semitic; cf. tav
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for tau

British Dictionary definitions for tau

/ (tɔː, taʊ) /


the 19th letter in the Greek alphabet (Τ, τ), a consonant, transliterated as t

Word Origin for tau

C13: via Latin from Greek, of Semitic origin; see tav
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Medicine definitions for tau



The 19th letter of the Greek alphabet.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.