tau

views updated Jun 08 2018

tau / tou; tô/ • n. the nineteenth letter of the Greek alphabet (Τ, τ), transliterated as ‘t.’ ∎  (Tau) [followed by Latin genitive] Astron. the nineteenth star in a constellation: Tau Ceti. ∎  (in full tau particle or tau lepton) Physics an unstable subatomic particle of the lepton class, with a charge of −1 and a mass roughly 3,500 times that of the electron.

tau

views updated May 09 2018

tau the nineteenth letter of the Greek alphabet. It was sometimes used in the sense ‘last letter’, as tau was originally in Greek.

The word is also used for the ankh of ancient Egyptian symbolism.
tau cross a T-shaped cross, both as a sacred symbol and in heraldry; it is the emblem of St Anthony of Egypt.

Tau

views updated May 29 2018

Tau Astronomy Taurus