During the 16th century, silver coins made in St. Joachimsthal, a town in Bohemia, a part of Czechoslovakia, were thought to contain the purest silver. This prized coin became known as the Joachimsthaler, a word that was shortened to thaler.
In some places in Europe, the word became daler. This was the name of certain Spanish coins that were used in America before the Revolution. In 1785, when the United States Congress decided to start issuing money, they chose that word, now spelled dollar, for the unit of currency.
Ten-daler Swedish coins, issued in 1644, weighed over 43 pounds each!