Poundal and pound
A poundal is the force required to give a mass of 1 pound (1 lb) an acceleration of 1 foot per second per second (1 ft/s2). 1 poundal equals 0.1382 newtons.
A pound is the force applied on a mass of 1 pound (1 lb) by the acceleration due to gravity. It is a non-technical unit of force and is also called the weight.
These units of force are in the English system and are seldom used in scientific measurements.