What does poundal mean?
A poundal is a former unit of force, used in the foot-pound-second system. It equals the force needed to accelerate a one-pound mass by one foot per second per second, and is approximately 0.138 newtons. The unit survives mainly in historical engineering texts, where it appears in compound units for pressure, viscosity, and energy. Its name joins pound with the suffix -al. Unlike the familiar pound-force, which is the force exerted by gravity on a one-pound mass, a poundal is defined through mass and acceleration in imperial units. The distinction matters in older mechanical calculations and also makes the word memorable. Today, SI units and the pound-force have largely replaced it. A reader encountering “poundal” in an engineering manual should recognize it as a historical force unit, not another spelling of “pound” or “pound-force.”
nounA former English unit of force equal to the force required to accelerate a mass of one pound at one foot per second per second. One poundal is approximately 0.138 newtons.
- A unit of force equal to that required to accelerate a one-pound mass at one foot per second per second, used especially in the foot-pound-second system.
"The engineering manual expresses the pressure as twelve poundals per square inch."
"The manual lists a pressure of twelve poundals per square inch."
"The lecturer explained that one poundal is the force needed to accelerate one pound at one foot per second squared."
The plural is grammatically standard but uncommon.
"Several poundals of force act on the suspended mass."
The poundal literally puts the pound into force: it is the force needed to accelerate one pound by one foot per second every second.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does poundal come from?
The word was coined in the nineteenth century from pound and the unit-forming suffix -al, within the English force-unit system based on the foot, pound, and second. Its structure reflects its definition: a poundal is the force required for a one-pound mass to accelerate one foot per second squared. The broader English family containing pound traces through Latin pondus, meaning “weight,” and includes cognates such as ponder and impound.
How poundal is actually used
Poundal is technical, formal, and now largely confined to historical engineering literature. In modern usage it may appear in the plural, though the unit is usually written in the singular.
Easily confused with poundal
A pound is a unit of mass, whereas a poundal is a unit of force defined by a pound mass accelerating at a specified rate.
A pound-force is the gravitational force on a one-pound mass, while a poundal is defined through mass and acceleration in the foot-pound-second system.