tau definition by Webster's New World
Origin: Middle 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
tau definition by American Heritage Dictionary
- The 19th letter of the Greek alphabet. See Table at alphabet.
- 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.
Origin: Greek, of Phoenician origin; see tww in Semitic roots.