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West Germanic gemination


West Germanic gemination was a sound change that took place in all West Germanic languages around the 3rd or 4th century AD. It affected consonants directly followed by /j/, which were generally lengthened ("geminated", came to be held longer) in that position. Because of Sievers' law, only consonants immediately after a short vowel were affected by the process.

When followed by /j/, consonants were lengthened (doubled). The consonant /r/, whether original or from earlier /z/ through rhotacization, was generally not affected; it occasionally shows gemination in Old High German, but inconsistently and this may be an analogical change. In contrast, the second element of the diphthongs iu and au was still underlyingly the consonant /w/ at this time, and therefore was lengthened as well.

In Proto-Germanic, /j/ only appeared at the beginning of a syllable, primarily as the onset of a variety of suffixes and endings. It alternated with its syllabic counterpart /ij/ in accordance with a phonological rule known as Sievers' law. This law states that consonantal /j/ appeared after a "light" syllable: one that contained a short vowel followed by at most one consonant. The syllabic allomorph /ij/ appeared after "heavy" syllables, which included syllables containing a long vowel, a diphthong, or ending in more than one consonant. As the gemination itself required the consonant to be directly followed by /j/, it therefore affected only light syllables; heavy syllables were not changed. Compare, for example, the Germanic verbs *fūlijaną "to defile" and *fuljaną "to fill, to make full", which appear in Old English as fȳlan and fyllan respectively, and in Old High German as fūlen and fullen; the first verb shows no gemination, while the second does.


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