Diez

Diez is the Spanish word for the number ten. It functions as a cardinal numeral and appears in many phrases involving counting, measurement, dates, and percentages. For example: diez días (ten days), diez euros (ten euros), and diez por ciento (ten percent). In compound numbers, diez serves as the base from which other numbers are built, and it also figures in expressions like los diez mejores (the ten best). The word underpins the decimal system, which is the standard for counting and arithmetic in Spanish.

Etymology and cognates: Diez comes from Latin decem, via Vulgar Latin into Old Spanish. Its cognates include Portuguese dez, French dix, Italian dieci, and Romanian zece, reflecting a common Romance-language origin.

Pronunciation and forms: Diez is pronounced with a soft d and a voiced z in many dialects; in Castilian Spanish the final z is pronounced as a theta [θ], while in most Latin American varieties it is an [s]. The numbers 11–15 have unique forms (once, doce, trece, catorce, quince); 16–19 are formed as dieci- (dieciséis, diecisiete, dieciocho, diecinueve). The word diez also appears in adjective- or numeral-based phrases describing multiples of ten, such as diez por diez (ten by ten).

Other uses: Diez is a common surname in Spanish-speaking regions. It can occur in place names and personal names, but as a numeric term it denotes the quantity ten rather than a proper noun.