Food and Recipes Kitchen Assistant WATCH: Here's Why Pound and Ounce are Abbreviated as "lb" and "oz" By Melissa Locker Melissa Locker Melissa Locker writes about food, drinks, culture, gardening, and the joys of Waffle House Southern Living's editorial guidelines Updated on May 9, 2023 Fact checked by Isaac Winter Fact checked by Isaac Winter Isaac Winter is a fact checker. He graduated from Lake Forest College in 2020 with a degree in English Literature. While in college, he was the Editorial Head of the school's literary magazine, Tusitala, for two years. Recently, he worked as an AmeriCorps employee at Above and Beyond Family Recovery Center in Chicago. There he helped set up a food pantry in the West Garfield Park neighborhood. brand's fact checking process Share Tweet Pin Email When you're reading through a recipe, we've all gotten used to seeing teaspoon abbreviated as "tsp" and pints are "pt.", but have you ever wondered how the word pound was abbreviated as lb? It's an odd choice, since they don't have any letters in common. Or what about ounce shortened to "oz." Where did that stray "z" come from? To find out it requires a trip through English language history. The word "pound" comes from ancient Roman when the unit of measure was libra pondo, which meant "a pound by weight." The English word "pound" draw from the pondo part of the phrase, according to the BBC. However, the abbreviation "lb" is derived from the libra part of the word. Similarly, that's why the symbol for the British pound is £, or an L with a line through it, because it also comes from libra pondo and, according to the BBC, "the pound's value originally equated to the price of a pound of silver." That's not the only form of currency to take its name from the old measurement. The former Italian currency the "lira" also derives from libra. SharonWills/Getty Images If all this talk of libra is setting off a light bulb in your head, that's because it's also the name of seventh sign of the zodiac, which is typically symbolized by scales. That's because the sign is associated with balance, and is related to weights and measurements. As for the word ounce, according to the Encyclopedia Brittanica, it originates from the Latin word uncia, which was the name for both a Roman unit of weight and length. According to The Week, uncia was borrowed by the Anglo-Norman French as "ounce" and then lent to their neighbors in England. The abbreviation, though, came from Medieval Italian, who had taken the Latin word uncia and turned it into onza, introducing the "z" into the word. It's unclear exactly why the "z" shows up in English abbreviations, but it's clear that it came from Medieval Italian and then stuck around. Frequently Asked Questions Is lb. metric or imperial? Pounds (lb.) are a part of the Imperial measurement system. The Metric system equivalent is kilograms. What is the plural abbreviation of pounds? The abbreviation for one pound is lb., but the plural is also lb. Generally, abbreviated measurements do not contain a plural, but some guidelines except the abbreviation of lbs. as correct. Was this page helpful? Thanks for your feedback! Tell us why! Other Submit Sources Southern Living is committed to using high-quality, reputable sources to support the facts in our articles. Read our editorial guidelines to learn more about how we fact check our content for accuracy. BBC News. A short history of the pound. Brittanica. Ounce. The Week. Why are pound and ounce abbreviated as 'lb' and 'oz'?