The English word 'pound' — in its senses of a unit of weight and a unit of currency — entered the language in the Old English period as 'pund,' borrowed from Proto-Germanic '*punda-,' which was itself an early borrowing from Latin 'pondo.' The Latin word is the ablative form of 'pondus' (weight), which derives from 'pendere' (to weigh, to hang). 'Pound' is thus one of the oldest Latin loanwords in the Germanic languages, entering before the fall of the Roman Empire.
The Latin phrase underlying the word was 'libra pondo' — literally 'a pound by weight.' This two-word phrase split into two separate English inheritances: 'pound' comes from 'pondo,' while the abbreviation 'lb.' comes from 'libra.' The zodiac sign Libra (the scales) is the same Latin word, and its symbol — a balance scale — visually depicts the apparatus that made 'pound' and all its relatives possible.
The Germanic borrowing of Latin 'pondo' was remarkably widespread. German 'Pfund,' Dutch 'pond,' Swedish 'pund,' Danish 'pund,' Norwegian 'pund,' and Icelandic 'pund' all descend from the same Proto-Germanic adaptation. This breadth indicates that the word was borrowed during the period of Roman-Germanic contact (roughly first through fourth centuries CE), when Roman weights, measures, and commercial practices were adopted across northern Europe.
As a unit of weight, the pound has had many different values across history. The Roman libra was approximately 328.9 grams. The modern avoirdupois pound (used in the United States and United Kingdom) is defined as exactly 453.59237 grams (16 ounces). The troy pound (used for precious metals) is approximately 373.2 grams (12 troy ounces). The apothecaries' pound was identical to the troy pound. These variations reflect centuries of local and regional standardization efforts
The monetary pound sterling has a direct connection to the weight pound. In the eighth century, one pound of sterling (high-purity) silver was divided into 240 pennies (denarii). This system — pounds, shillings, and pence (£/s/d, from libra/solidus/denarius) — persisted in Britain until decimalization in 1971. The '£' symbol is a stylized 'L' for 'libra,' completing the circle: the currency symbol comes from the Latin word that also gave the abbreviation 'lb.'
The connection between 'pound' and the broader 'pendere' family is sometimes overlooked because 'pound' looks and sounds Germanic. But the chain is clear: 'pound' from 'pondo' from 'pondus' from 'pendere.' This makes 'pound' a distant relative of 'ponder' (to weigh mentally), 'ponderous' (heavy), 'preponderance' (outweighing), 'pension' (a payment weighed out), 'expend' (to weigh out money), 'depend' (to hang from), 'suspend' (to hang up), 'pendant' (a hanging thing), and 'pendulum' (a hanging weight). The entire family radiates from the single act
The verb 'to pound' (to strike heavily and repeatedly, as in pounding a nail or pounding on a door) is a separate word with a different etymology. It comes from Old English 'punian' (to crush, to pound), probably of Germanic origin and unrelated to Latin 'pondo.' The similarity is coincidental, though the two words have coexisted in English for over a millennium.
The word 'pound' as an enclosure for stray animals (the 'dog pound' or 'impound lot') has yet another separate origin, from Old English 'pund' meaning an enclosure, related to 'pond.' Three different etymological streams — Latin weight, Germanic striking, and Old English enclosure — converge in the single English spelling 'pound,' making it one of the most polysemous words in the language.
As both a unit of weight and a unit of currency, 'pound' embodies the ancient equivalence between mass and value — the principle that money is, or was, a quantity of precious metal, and that paying meant weighing. That equivalence has been gone for centuries (modern currencies are fiat, backed by government authority rather than metal weight), but the word endures, a Latin fossil embedded in everyday English commerce.