The commonly held belief is that pound is abbreviated “lb” is that when one picks up something heavy, i.e. weighs many pounds, the person groans, “lllllbbbbbb.” However, I have learned that, in fact, “lb” stands for libra, a Latin word that describes a Roman measure of weight similar to a pound. The symbol for the British currency (£ or ₤) is actually a crossed out letter “L” also representing libra. The term “pound” comes from the Latin word pendere which means “to weigh.”

Thanks Melissa for inventing the mythological origin and Wikipedia for setting the record straight.