Stigma (letter) Stigma (letter) Stigma (ϛ) is a ligature of the Greek letters sigma (Σ) and tau (Τ), which was used in writing Greek between the Middle Ages and the 19th century. It is also used as a numeral symbol for the number 6. In this unrelated function, it is a continuation of the old letter digamma (originally Ϝ, cursive form ), which had served as a numeral since antiquity and was conflated with the σ-τ ligature in the minuscule handwriting of the Middle Ages. The στ ligature (, ) was one of many ligature forms that came into widespread use as
Pound-foot (torque) unit is often still referred to as the foot-pound (ft⋅lbf). Similarly, an inch-pound (though should be more correctly as "pound-inch") is the torque of one pound of force applied to one inch of distance from the pivot, and is equal to of a pound-foot. It is commonly used on torque wrenches and torque screwdrivers for setting specific fastener tension. Pound-foot (torque) A pound-foot (lbf⋅ft) is a unit of torque (a pseudovector). One pound-foot is the torque created by one pound of force acting at a perpendicular distance of one foot from a pivot point. Conversely one pound-foot is the moment