Dollar is the name of the unit of currency used by more than 20 countries and territories, of which the best known is the United States Dollar (USD). The word goes back to a silver coin first struck in Bohemia in 1520, and over five centuries it has been attached to coins and banknotes in Europe, the Americas, Africa, Asia and the Pacific.
This entry is about the name and the family of currencies that share it. Each dollar is a separate currency, issued by its own central bank or monetary authority, with its own value and exchange rate; a Canadian dollar and a Hong Kong dollar have nothing in common beyond the word. Where people say "the dollar" without qualification, they almost always mean the US currency, which is covered in its own entry.
Dollar in plain terms
Dollar is a bit like a popular first name. Many unrelated people are called Mohammed, John or Maria, and you need a surname to know which one is meant. In the same way, many countries call their money the dollar, and you need the country to know which one you are holding.
The name spread because one coin became famous and trusted. People used it so widely that its name stuck, and when new countries designed their own money, they picked a name everyone already knew. Today the dollars of different countries buy very different amounts, so prices are usually written with a country code, such as US$, C$ or A$, to avoid confusion.
From Joachimsthaler to dollar
In 1520 the counts of Schlick began minting large silver coins from the mines at Joachimsthal, a valley town in Bohemia now called Jáchymov in the Czech Republic. The coins were called Joachimsthaler, "of Joachim's valley", which was soon shortened to thaler. Thalers were copied across the German lands and beyond, and the name passed into other languages as daler, daalder and, in English, dollar.
The coin that carried the name around the world was Spanish. Spain's silver piece of eight reales, a multiple of the Spanish real minted from the 16th century mainly in Mexico and Peru, was similar in size to the thaler, and English speakers called it the Spanish dollar. It circulated through the Americas, the Caribbean and the trading ports of Asia, and it became a model for later currencies, including the Mexican peso (MXN).
When the United States chose its own unit, it adopted the familiar name. The Continental Congress approved the dollar in 1785, and the Coinage Act of 2 April 1792 defined it as 371.25 grains of pure silver, matched to the Spanish coin. Later, the paper notes printed during the Civil War gave the US dollar its nickname, the greenback. The old silver dollar's reach also shows in East Asia: the names of the Chinese yuan (CNY) and the Japanese yen (JPY) come from a word meaning "round", a reference to round silver dollar coins.
Currencies called dollar today
As of 2026, the dollar name is used by national currencies including:
- North America and the Caribbean. The US dollar, the Canadian dollar (CAD), the Bahamian dollar (BSD), the Jamaican dollar (JMD), the Trinidad and Tobago dollar (TTD) and the East Caribbean dollar (XCD), shared by eight island economies, as well as the Barbadian, Belize, Bermudian and Cayman Islands dollars.
- Asia. The Hong Kong dollar (HKD), the Singapore dollar (SGD), the New Taiwan dollar (TWD) and the Brunei dollar.
- Oceania. The Australian dollar (AUD), the New Zealand dollar (NZD), and the Fijian and Solomon Islands dollars.
- Africa and South America. The Liberian dollar (LRD), the Namibian dollar, and the Guyanese and Surinamese dollars.
Several of these are tied to another currency. The Hong Kong dollar is held in a narrow band against the US dollar by the Linked Exchange Rate System (Hong Kong), a currency board, and others use a currency peg. Some names have also disappeared: the Zimbabwean dollar (ZWL) was abandoned after hyperinflation in 2009, revived in 2019 and replaced by the ZiG in 2024, and Slovenia's tolar, another descendant of the thaler, gave way to the euro in 2007.
Some countries use the US dollar itself rather than a dollar of their own, a practice called dollarization; Ecuador, El Salvador and Panama are well-known examples.
The dollar sign
The $ dollar sign, an S with one or two vertical strokes, is used for most dollars and also for many pesos, including those of Mexico, Chile and Colombia. Its origin is not certain. The explanation most historians favour is that it grew out of the handwritten abbreviation "ps" for pesos in Spanish-American trade during the 18th century, with the letters gradually merging into one symbol. Because the same sign serves many currencies, financial documents use ISO 4217 codes such as USD, CAD and AUD, or prefixes such as US$, to remove doubt.
The dollar name in global finance
In markets the plain word "dollar" refers to the US currency, which is the main reserve currency and the anchor of many exchange-rate systems, a role it took on under the Bretton Woods System after 1944. Terms built on it include Eurodollar deposits held outside the US, dollar liquidity and dollar-pegged stablecoins. Like most modern money, every dollar in use today is a fiat currency, no longer convertible into silver or gold.