# xxi

CEFR C2 · Noun

Source: https://englishreference.com/word/xxi
Updated: 2026-05-19

## Definition

the Roman numeral for the number twenty-one. You might see this in old books or on historical signs.

For teachers: the Roman numeral representing the cardinal number twenty-one. Used primarily in historical, legal, or formal contexts.

## Examples

- The chapter is labeled as Chapter XXI.
- The historian noted that the event occurred in the year XXI of the reign of the emperor.
- The manuscript was dated to the year XXI, though modern scholars suggest the actual date may be several decades later due to the shifting calendar system.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.