Lbs...the L derives from the french livre which was roughly the same weight. I think the b is for British. OZ is probably just a contraction...it follows the law of consonental shift. The d for old penny is reputed to come from denarius, the Roman silver coin
French livre comes from the Latin libra, hence the lb. It's also the reason we use �, a stylised L for cash pound as well. Oz is a contraction, but from the Italian onza, ounce. And d is definitely from denarius.