ABSTRACT
Central notion of the historical linguistic description of the Neogrammarians. The use of this term is based on the assumption that-in analogy to natural scientific regularitiescertain sounds of a given language undergo certain phonetic changes in the same way without exception. Such changes have a physiological basis and occur under the same conditions, e.g. the Germanic sound shift ( Grimm’s law; also umlaut, diphthongization). In those cases in which exceptions are ascertained in spite of the law, analogy and language mixing, i.e. adoptions from other varieties of languages ( sound substitution) are considered to be at cause.
