Millesimo

Millesimo is the Italian term for the thousandth part of a quantity, derived from mille meaning thousand and the suffix esimo indicating an ordinal. It denotes 1/1000 of a unit (0.001) and is used in contexts where precise fractions are important.

A prominent use of millesimo is in the trade and valuation of precious metals. Purity is expressed in millesimi, as in oro a 750 millesimi (75% gold) or oro a 999 millesimi (99.9% gold). The same applies to other metals, for example argento 925 millesimi (92.5% silver). In jewelry and coinage, millesimi provide a standardized way to indicate fineness.

In viticulture and wine labeling, millesimo is used to denote the vintage year of a wine or sparkling wine. A bottle described as millesimo 2010 indicates the year of harvest, signaling the vintage rather than the age of the wine.

Beyond these contexts, millesimo can appear in general measurement to refer to a thousandth part of any unit, though in everyday usage decimal notation or dedicated subunits (such as milliliters for liters) are more common. The term remains primarily a technical descriptor of precision and fineness.

The plural form is millesimi, used when referring to multiple thousandths or several fineness standards; millesimo remains the singular form.