
Grimm’s law (also known as the First Germanic Sound Shift) is a set of sound laws describing the Proto-Indo-European (PIE) stop consonants as they developed in Proto-Germanic in the 1st millennium BC. First systematically put forward by Jacob Grimm but previously remarked upon by Rasmus Rask, it establishes a set of regular correspondences between early Germanic stops, fricatives, and the stop consonants of certain other centum Indo-European languages.
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Verner’s law describes a historical sound change in the Proto-Germanic language whereby consonants that would usually have been the voiceless fricatives *f, *þ, *s, *h, *hʷ, following an unstressed syllable, became the voiced fricatives *β, *ð, *z, *ɣ, *ɣʷ. The law was formulated by Karl Verner, and first published in 1877.
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