Usually POUND (when it refers to weight) is abbreviated "lb.", although I have sometimes seen "lbs." The Latin word for pound is LIBRA, and that word was once used in English when referring to money. Apparently our word "pound" comes from the Latin word "pondo" which means weight; the Latin expression seems to have been "libra pondo" for "a pound in weight" (as opposed to a pound in money). The Italian monetary unit, the lira, as well as the British pound were coins that were once equivalent to a pound of a precious metal. Both are abbreviated with a fancy capital L (not followed by a period). The story of the terminology can be found in the OXFORD ENGLISH DICTIONARY, and also (under pound, libra and in the appendix) in the AMERICAN HERITAGE DICTIONARY.