Poundal
The poundal (symbol: pdl) is a unit of force that is part of the foot–pound–second system of units, in Imperial units introduced in 1877, and is from the specialized subsystem of English absolute (a coherent system).
The poundal is defined as the force necessary to accelerate 1 pound-mass to 1 foot per second per second. 1 pdl = 0.138254954376 N exactly.