The symbol for torque is 'TAU' (3 letters). It is a Greek letter that is used in physics to represent the ratio of a force's moment to its distance from the axis of rotation. It is also used in mathematics and engineering to represent the ratio of a force's moment to its distance from the point of application. In addition, it is used in chemistry to represent the ratio of a molecule's dipole moment to its distance from the center of the molecule.