from The American Heritage® Dictionary of the English Language, 4th Edition
- adj. Of, relating to, or characteristic of the U.S. Customary and British Imperial systems of measurement based on the foot, the pound, and the second as the fundamental units of length, mass, and time.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- adj. Of or relating to a measurement system that uses the foot as a measure of distance, the pound as a measure of force, and the second as a measure of time. Abbreviations: ft-lb-s, fps, f.p.s.
- n. A unit of mechanical power, equal to that required to raise one pound through a distance of one foot in one second.
Sorry, no etymologies found.
Likewise, despite the metric unit of packaging being in force for the last half-century, some companies use metric-convertibles of old foot-pound-second units to pack medicines.