It is well-attested that floating tones can associate across a word boundary, but it is typologically unusual for floating weight units to do so. The Nuer language presents a floating suprasegmental component (FSC), which is part of lexical morphemes, and includes a unit of quantity and a High tone. This component is located at the left edge of nouns and is realised primarily across a word boundary on a preceding vowel. This article examines the FSC through a phonological analysis and a production study with eight speakers. These investigations reveal how the FSC interacts with the specifications for vowel length and tone of the adjacent context. Specifically, the weight unit of the FSC lengthens a preceding word-final short vowel, and its High tone combines in a compositional manner with tone of this preceding context. Comparisons with related languages suggest that the FSC developed out of a word-initial vowel /a/.

Nuer (ISO 6393: nus/Glottocode: nuer1246) is a Nilo-Saharan language (Nilo-Saharan, Eastern Sudanic, Nilotic, Western, Dinka-Nuer). The sound system of Nuer is of particular interest because the language has a rich inventory of vocalic and suprasegmental distinctions, including a large number of vowel phonemes, a voice quality contrast (modal versus breathy), three levels of vowel length, and a tonal inventory that interacts with the voice quality contrast.