Dinka is a Western Nilotic language within the Nilo-Saharan family. There are over two million speakers (Gordon 2005). The Dinkas live along the banks of the White Nile and its tributaries in Southern Sudan. There are also communities elsewhere within Sudan, in particular in the capital Khartoum, and abroad. Cows play a key role in the Dinka economy, and also in the sociocultural system. Four major dialect areas are commonly distinguished: Padang, Rek, Agar, and Bor. The variety of Dinka represented here – Luanyjang or, as in Roettger & Roettger (1989), Luac – is part of the Rek dialect group. The term Luanyjang ‘Luac Dinka’ refers in the first place to a section within the Dinka ethnic group, and by extension also to their variety of the Dinka language. The main Luanyjang town is Wuncuei, located about 170 kilometers east of the city of Wau. Luanyjang has around 15000 speakers according to Ethnologue (Gordon 2005), although the current number is likely to be much higher.

Discussions of the psycholinguistic significance of regularity in inflectional morphology generally deal with languages in which regular forms can be clearly identified and revolve around whether there are distinct processing mechanisms for regular and irregular forms. We present a detailed description of Dinka's notoriously irregular noun number inflection and suggest that no pattern can usefully be designated as regular. Psycholinguistic studies of Dinka would make a valuable contribution to our understanding of inflectional morphology crosslinguistically.