eikosi

Eikosi (Greek: εἴκοσι) is the modern Greek word for the cardinal number twenty. It originates from the ancient Greek numeral system, where the compound εἴκοσι derives from the prefix εἰ‑ (“in”) combined with the root *κισ‑, a variant of the Indo‑European root *kwéw “four”, reflecting the historical counting method of “two tens”. In classical Greek, the number twenty was expressed as εἴκοσι, a form that has persisted with little alteration into contemporary Greek.

In the Greek numeral system, eikosi is written with the letters κʹ (kappa with a numeral sign) and is used in both spoken and written contexts to denote the quantity of twenty units. The term appears in a range of applications, from everyday counting and measurement to literary and historical texts, where it may indicate ages, years, or group sizes. In modern Greek education, eikosi is taught early as part of basic arithmetic, and its pronunciation follows the standard Greek phonological rules: [ˈi.ko.si].

The word also features in compound numbers and ordinal forms; for example, εικοστός (eikostós) means “twentieth”. In contemporary Greek culture, the number twenty often marks milestones such as the legal age for voting and the celebration of a “twentieth birthday”, where eikosi is referenced in both formal and informal discourse.