centiliter

The centilitre is a labelling unit, and its territory is the European drinks aisle: wine at 75 cl, spirits at 70 cl, with the capacity often moulded into the glass itself. Bartending adopted it as a recipe unit, and the International Bartenders Association writes its official cocktail specifications in centilitres, so the IBA margarita reads 5 cl tequila, 2 cl triple sec and 1.5 cl lime juice. A bar jigger sold in Europe is typically marked 2 and 4 cl where an American one is marked in fluid ounces.

The transatlantic trap is the spirits bottle. The standard European bottle is 70 cl while the standard American one is 750 mL, a 7% difference that is easy to miss because both are simply "a bottle" of the same product, and duty-free litre bottles are a third size again. The prefix is itself a curiosity: outside the centimetre and the centilitre, centi- has nearly vanished from daily life, because science and engineering prefer prefix steps of a thousand. This site's volume conversions treat the centilitre as what it is, exactly 10 mL, and the litre page tells the longer story of the unit it divides.