Germanic spirant law

In linguistics, the Germanic spirant law or Primärberührung is a specific historical instance of dissimilation that occurred as part of an exception of Grimm's law in the ancestor of the Germanic languages.

The law affects the various series of stops in Proto-Indo-European that underwent Grimm's and Verner's law. If these were immediately followed by a t or s, they changed to a voiceless fricative (spirant):

Under normal conditions, any voiced stop would likely have been devoiced before /t/ and /s/ in Indo-European times. This means that all three Indo-European series of stop consonants (aspirated, voiced and voiceless) had already merged before these two consonants, so that for example the sequences /bʰt/, /bt/ and /ɡʰt/, /ɡt/ had already become /pt/ and /kt/ in certain late Proto-Indo-European dialects. Likewise, /bʰs/, /bs/ and /ɡʰs/, /ɡs/ had become /ps/ and /ks/. Compare for example Latin scribere "to write" and legere "to gather, read" with their past participles scriptus and lectus. Examples before /s/ are also numerous, compare again Latin scribere and its perfect scripsī, or pingere "to paint" and pinxī, and also the genitive noun form regis and its nominative rēx "king".

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