This word has three meanings, and they're all closely related. It can refer to the pound, the unit of currency in the United Kingdom and some of its dependencies. It can refer to a grade of silver. It can refer to a high level of character, for example, "He is a man of sterling character." In Medieval England, a common type of coin was a silver penny. It was stamped with a small star - in Medieval English, a sterling. The coin itself came to be called a sterling. People who dealt in large payments would measure them in pounds of silver pennies. Eventually, a pound of sterlings became a standard unit of currency itself - a pound sterling. When the government standardized the amount of silver that the pennies had to contain, silver of that quality came to be called sterling silver, and anything of reliable, standard quality was said to be sterling.
(Will be published in the October 2009 issue of Denver's Community News.)
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