How did the (lb) become the abbreviation of pound (weight)

The origin is in the Latin word libra, which could mean both balance scales and also a pound weight, or libra pondo, the second word being the origin of our pound.

This is also where the zodiac sign Libra came from.

I wαs just gonnα sαy thαt synnen-- pshht--thαnks for beαting me to the punch:p