Allomorfie

Allomorphie, or allomorphy, is the variation in the phonetic realization of a morpheme, the smallest unit of meaning, across different contexts. Different surface forms that realize the same morpheme are called allomorphs. Although they sound different, these variants carry the same grammatical function and meaning. Allomorphy is a central topic in morphophonology, the study of how sound and grammar interact in inflection and word formation.

Allomorphs arise when phonological context, phonotactics, or historical change conditions the surface form of a morpheme. They can be regular and predictable through phonological rules or irregular and lexicalized. A key distinction is between allomorphy and allophony: allomorphs are tied to a morpheme and reflect morphologically meaningful variation, while allophones are variants of a phoneme that do not change meaning.

A classic example is English plural morphology, which has three allomorphs of the plural suffix: the /s/ pronounced [s] after voiceless sounds (cats), the /z/ pronounced [z] after voiced sounds (dogs), and the /ɪz/ or [ɪz] pronounced after sibilants (buses). Another well-known case is the past tense suffix -ed, realized as [t] after voiceless consonants (walked), [d] after voiced consonants (played), or [ɪd] after alveolar stops (wanted). Some nouns also exhibit zero allomorphy, where the plural is not overtly marked (e.g., sheep, deer).

Allomorphy occurs in many languages and reflects how morphology interacts with phonology to shape surface forms while preserving abstract grammatical meaning.