The Nuer vowel grade system

In Nuer, a highly fusional and predominantly monosyllabic West Nilotic language, morphology is expressed primarily by stem-internal changes that affect vowel quality, voice quality, tone, vowel length and the stem-final consonant. This paper focuses on the interrelated alternations in vowel quality and voice quality, showing how these two parameters are used to encode inflection and derivation. Because the relation between the sets of the participating vowels is not systematic in a phonological sense, the alternations are analysed by postulating abstract morphological categories termed vowel grades. The proposed analysis enables us to unambiguously categorise the patterns of morphological marking on verbs, nouns, and adjectives. In addition, it simplifies the vowel inventory relative to earlier accounts. Finally, the proposed analysis contributes to our understanding of the diachronic development of vocalic phenomena in the West Nilotic languages.