GRIMM'S LAW is the name given to the rule which regulates the Lautverschiebung, or permutation of certain primitive consonants, which takes place in the Teutonic languages. The law, as finally formulated by Jakob Grimm, is that if the same roots or words exist in San skrit, Greek and generally in Latin, Celtic, Let tic and Slavonic, and also in Gothic, English, Dutch and other Low German dialects on the one hand, and in Old High German on the other, the following correspondences are to be expected: (1) Gothic has a soft mute, and High German a hard mute, in place of the corres ponding aspirate in Sanskrit and Greek; (2) Gothic has a hard mute, and High German an aspirate, in place of the corresponding soft mute in Sanskrit and Greek; (3) Gothic has an aspirate, and High German a soft mute, in place of the corresponding hard mute in Sanskrit and Greek. Thus, a primitive th becomes d in Low German, and t in High German, as in the words thugater, daughter, tochter. A primitive d be comes t in Low German, and z in High Ger man, as in duo, two, zwie; or dens, tooth, zahn; or deccm, ten, zehn. A primitive t becomes th in Low German, and d in High German, as in fres, three, drci; or tu, thou, du; or tennis, thin, dimn. Similar changes affect the labials and gutturals, as in pecus, fee, vieh; pater, father, miter; fagus, beech, puocha; and in ()ruins, eghe ("eye"), quis, who, wer ; or khortus, .garden, korto. The normal changes are set forth in the following table: Labials Dental, Gutturals Greek, et b ph t d th k H kh Gothic etc f b th t d (h) k g Old High German.. b (v) p f p d s t 11(h)ch k The credit of the discovery of the Laid — verschiebung is not wholly due to Jakob Grimm.
Ihre and Rask had discovered, as early as 1818, the law of the transmutation of consonants in Greek and Gothic, while Grimm, in the second edition of his 'Deutsche Graiumatik) which ap peared in 1822, added the corresponding changes in Old High German, and formulated the law as it now stands.
Grimm's Law may be interfered with by the action of other laws, especially by the position of the accent, as formulated in Verner's Law (q.v.). Thus trailer is accented on the first syl lable and pater on the second, consequently, though we have brother and father in English, we find bruder and voter in High German. The accent in patir has interfered with the regular action of the Lautverschiebung, and prevented the normal change of t to d from taking place.
Thus Grimm's Law may be defined as the statement of certain phonetic facts which happen invariably unless they are interfered with by other facts. The great use of Grimm's Law, in addition to the identification of words in differ ent languages, is in the detection of loan words. Any etymology which violates Grimm's Law, as qualified by other phonetic laws, must be rejected unless it can be explained as a loan word. The causes which brought about the changes formulated in Grimm's Law are ob scure. They are probably due to the settle ment of Low German conquerors in central and southern Germany. Consult Douse, 'Grimm's Law : a Study of (1876); Max Muller, 'Lectures on the Study of Lan e' (2d series, lecture v, 1864) ; Morris, Outlines of English Accidence' (Chap. 2, 1872).