Alfermann's Law (named after the fictional linguist Juliane Alfermann) is a complex change in the phonology and morphology of the North Hesperic languages. In these languages, non-paradigmatic final *a is lost; this loss affected inanimate a-stem nouns (e.g. *khara > *khar 'stone') and oblique case endings (e.g. *xnarana > *xnaran 'man' (dative).
In animate nouns and verb endings, number inflection was reorganized such that *-a marked the singular, *-u dual and *-i plural in all cases. This involved suffixation of *-a to i-stem and u-stem animate nouns (e.g. *xasi > *xasia 'star'). Also, the objective dual and plural endings are regularized. The nominal paradigm thus changed from the Proto-Hesperic paradigm
to this type:
In Hercynian and Alpianic, this paradigm underwent a further change due to the neutralization of final nasals as *-n. This change led to the merger of the old dative and objective case, and the shift of the old partitive case to the meaning of a dative case.
The adverb-forming suffix *-s on adjectives also became *-i, the source of the Old Albic instrumental case.
The South Hesperic languages did not undergo this change.