Verner's law[vʉr′nərz, ver′-]
Verner's law definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
an explanation for a series of apparent exceptions to Grimm's law, stating that the Proto-Germanic word-medial voiceless spirants (f, t̸h, h, s), derived from the Proto-Indo-European voiceless stops (p, t, k) and voiceless spirant (s), regularly became voiced (v, t̸h, g, z), respectively, and final (s) became (z), when the vowel immediately preceding these did not in Proto-Indo-European bear the principal accent of the word
Origin: formulated (1875) by Karl Verner (1846-96), Danish philologist
Verner's law definition by American Heritage Dictionary
A law stating essentially that Proto-Germanic noninitial voiceless fricatives in voiced environments became voiced when the previous syllable was unstressed in Proto-Indo-European. For example, both the th- and the -d of English third are descended from Proto-Germanic voiceless *th, but the second was voiced by Verner's Law.
Origin: After Karl Adolph Verner (1846-1896), Danish philologist.