2/6/12 ...Which Starts with L Which Stands for Pound?
Infrequently Answered Question #65: Why is pound abbreviated 'lb' when there's no L or B in the word?
A: It's confusing because 'lb' is not an abbreviation for the word pound, but an abbreviation of a Latin word for weight, libra. In which case the abbreviation makes sense. Sort-of. The word pound derives from the Latin pondo, "by weight." Why they took one Latin word for use and a different Latin word to abbreviate is something of a puzzle.
Libra also explains the symbol for British money, the pound. You know, £. It's a script L with a crossbar for Libra. This is found on a computer keyboard at option-3. And shift-3 gets you a different pound sign, #. Well, sort-of a pound sign as it's only a pound sign on a telephone. On a computer # stands for number, which is abbreviated 'no.' despite there being no O in number.
To go off on another tangent, the astrological symbol for Libra is not £ or # but a horizontal line with a hump in the middle over a straight line. Sort-of a pictogram of a balance scale. You won't find that on a computer keyboard so you'll have to type out the word. On a telephone pad you'd have to dial 5-4-2-7-2 to spell libra. Then again, there's no longer a dial on a phone to dial yet we say dial anyway.
Though you didn't ask, here's why ounce is abbreviated oz. even though there is no Z in ounce. It stands for the Italian onza, ounce. This comes from the Latin uncia, meaning one 12th, which is also the source of the term "inch."