Tau (noun)

The 19th letter of the Greek alphabet (Τ, τ), transliterated as "t" or "th".

Origin:

Late 19th century: from greek tau, the name of the letter t.

Examples:

1. Tau is the 19th letter of the Greek alphabet.
2. The Greek word for "tau" is spelled with the letter tau.
3. In physics, tau is the ratio of shear stress to shear strain.
4. In mathematics, the tau function is a function of the number of divisors of a number.
5. The Tau particle is a subatomic particle that decays into three charged pions.