Milésima

Milésima is a term used in Spanish and Portuguese to denote the fraction 1/1000 or, more broadly, the thousandth part. It functions as a feminine form of the ordinal or as a noun meaning one thousandth. For example, milésima parte corresponds to “the thousandth part,” and una milésima can stand alone as “one thousandth.”

Etymology and forms: The word derives from the Latin mille, meaning “thousand,” combined with the ordinal suffix -ésimo. The masculine counterpart is milésimo, while milésima is used with feminine nouns such as parte, posição, or medida.

Usage: Milésima appears in mathematical, scientific, and everyday expressions to express very small proportions. Common constructions include la milésima parte de la población (the thousandth part of the population) or milésimo de segundo (a thousandth of a second). In Portuguese, milésima and milésimo are used similarly, for instance, milésima parte or milésimo de segundo. The form agrees in gender with the noun it modifies.

Cross-language context: Related terms exist in other Romance languages, such as millesimo in Italian and millième in French, all conveying the sense of a thousandth. In English, thousandth is the direct equivalent.

See also: decimal notation, fractional parts, and the general prefix milli-, which denotes multiplication by one thousand. The concept of a thousandth is common across measurement, mathematics, and science, and milésima serves as the feminine form in contexts where a feminine noun is involved.