τ

Symbol

 * 1)  Torque.
 * 2)  Shear stress.
 * 3)  Optical depth.
 * 4)  An irrational constant defined as the ratio of the circumference of a circle to its radius, equal to the radian measure of a full ; approximately 6.283185307 (equal to 2π, or twice the value of π).
 * 5)  tauon
 * 6)  a voiceless dental plosive (IPA t̪).
 * 1)  a voiceless dental plosive (IPA t̪).

Etymology
Derived from its majuscule counterpart Τ.

Letter

 * 1) Lower-case tau, the 19th letter of the ancient Greek alphabet. It represented the voiceless unaspirated alveolar or dental plosive . It is preceded by σ and followed by υ.

Derived terms
See also tau

Letter

 * 1) The lower case letter tau (ταυ), the 19th letter of the modern Greek alphabet.