Grimm's Law

Grimm's Law, phonetic principle formulated by the German philologist Jacob Grimm in 1822. It describes the pattern of two stages of regular sound changes, known as the German consonant shift and the High German consonant shift. The first stage occurred between 2000 bc and ad 200, when certain consonants of the Germanic languages (to which English belongs) evolved from corresponding consonants in the Indo-European parent language. The second stage, between ad 500 and 700, occurred in the High German dialects of southern Germany from which modern (standard) German developed. According to Grimm's law, the ancient unvoiced p, t, and k became the English unvoiced f, th, and h, and the Old High German f, d, and h. Thus, taking Latin as an example of an earlier member of the Indo-European language group, the Latin pater became the English father and the Old High German Fater (modern German Vater). In addition, the ancient unvoiced b, d, and g changed to p, t, and k in English (for example, Latin dens, to English tooth) and kh in Old High German.

Grimm's law is important in that it demonstrates the development from the old Germanic languages of more recent languages such as English, Dutch, and Low German. It also shows that changes in a language and in groups of languages come about gradually and not as a result of random word changes. Grimm based his research on the 1818 treatise of the Danish philologist Rasmus Christian Rask, a discussion of the origin of Old Norse. Grimm's work was augmented by the explanations of stress shifts formulated by the Danish philologist Karl Adolf Verner. See Verner's Law.