\Laut"ver*schie`bung\, n.; pl. {-schiebungen}.
[G.; laut sound + verschiebung shifting.] (Philol.)
(a) The regular changes which the primitive Indo-European
    stops, or mute consonants, underwent in the Teutonic
    languages, probably as early as the 3d century b. c.,
    often called the {first Lautverschiebung}, {sound
    shifting}, or {consonant shifting}.
(b) A somewhat similar set of changes taking place in the
    High German dialects (less fully in modern literary
    German) from the 6th to the 8th century, known as the
    {second Lautverschiebung}, the result of which form the
    striking differences between High German and The Low
    German Languages. The statement of these changes is
    commonly regarded as forming part of Grimm's law, because
    included in it as originally framed.