Verner's law

noun

Ver·​ner's law ˈver-nərz- 

: a statement in historical linguistics: in medial or final position in voiced environments and when the immediately preceding vowel did not bear the principal accent in Proto-Indo-European, the Proto-Germanic voiceless fricatives f, þ, and χ derived from the Proto-Indo-European voiceless stops p, t, and k and the Proto-Germanic voiceless fricative s derived from Proto-Indo-European s became the voiced fricatives ƀ, ð, ǥ, and z represented in various recorded Germanic languages by b, d, g, and r

Word History

Etymology

after Karl A. verner, who formulated it

First Known Use

1878, in the meaning defined above