kirjaühikut

Kirjaühik is a term used in Estonian language contexts to denote the smallest unit of written language that carries a meaningful written form. In practice it corresponds to a grapheme or a basic unit of a writing system, such as a single letter or symbol, including letters with diacritics that are part of the Estonian alphabet (for example ä, ö, ü, õ). The concept helps distinguish what counts as a “character” in writing from the spoken sound or from a broader set of symbols.

In linguistics and typography, kirjaühik is often treated as synonymous with grapheme, the visual representation used in writing. This means that a single kirjaühik can be a simple, discrete character like a, b, or the diacritic letters, while more complex sequences may or may not be counted as one kirjaühik depending on the encoding and the analysis (for instance, a base letter combined with a diacritic could form a single grapheme cluster in typography even though it may be encoded as multiple code points in Unicode).

The notion is used across fields such as orthography, language education, typography, and natural language processing. When processing text digitally, counting kirjaühikud can be complicated by factors such as combining marks, ligatures, or emoji, which may form single grapheme units that span multiple code points.

See also: grapheme, letter, orthography, Unicode, typography.