František Kratochvíl*, David Moeljadi, Benidiktus Delpada, Václav Kratochvíl, and Jiˇ rí Vomlel Aspectual pairing and aspectual classes in Abui Abstract: This paper describes the aspectual classes in Abui, a Papuan language of the Timor-Alor-Pantar family. Abui innovated a system of aspectual stem pairing, realised by consonant mutation, vowel grading, and rime mutation. Although stem pairing is widespread (about 61% of the verbs alternate), about 38% of our 1330 verb sample are unpaired and immutable. Abui verbal stems combine with aspectual affixes, adverbs and auxiliary verbs, whose distribution is used here together with the stem types to describe aspectual classes, which are understood as lexicalisations of transitional possibilities of lexical items (e.g. inchoative-stative vs. inchoative-gradual.inchoative-stative). The paper takes the bidimensional approach to aspect distinguishing between properties associated with the perfective-imperfective system and other aspectual marking (cf. Sasse 2002). Combining the features of both types of aspectual marking, we construct in a bottom-up fashion the aspectual classes in Abui and also show that these may be further refined if contextual features such as valency or degree of change (affectedness) were included. A characteristic feature of the Abui system is the elaborate system of stative-inchoative verbs sensitive to scalar and change properties (e.g. instant vs. gradual). Abui telic verbs show sensitivity to the properties of the resulting state and are formally associated with stem alternation. Keywords: aspectual pairing, perfective-imperfective, aspectual classes, lexical aspect, Papuan, Timor-Alor-Pantar 1 Introduction This paper investigates the aspectual system in Abui (Glottolog: abui1241) which in- cludes a system of paired imperfective and perfective verbal stems that vary in their compatibility with other aspectual marking (e.g. aspectual affixes, adverbs, and auxil- *Corresponding author: František Kratochvíl, Palacký University Olomouc, Czechia David Moeljadi, Palacký University Olomouc, Czechia Benidiktus Delpada, Univesitas Tribuana Kalabahi, Indonesia Václav Kratochvíl, Jiˇ rí Vomlel, Czech Academy of Sciences, Institute of Information Theory and Automation, Czechia