This is a first descriptive grammar of Motuna - a Non-Austronesian language spoken by circa 16 thousand people (in 2000) in the “Siwai” area of the Bougainville Island, Papua New Guinea. It is one of the six languages belonging to the South Bougainville Family. This is written mainly on the basis of the analysis of narrative texts (three of which are given in Appendix) and other linguistic data provided by two Motuna speakers living in Australia.

Motuna has many unique typological characteristics (Chap 1). It has a small inventory of phonemes and a simple CV(C) syllable structure; morae play an important role in accent assignment, reduplication, and “dearticulation” of Ci/Cu syllables into three coda consonants (Chaps 2, 4 and 13). The language is both head- and dependent-marking - core arguments (S, O and A) are obligatorily cross-referenced by verbs, while A NP is optionally marked by an ergative (instrumental) case suffix (Chap 3).

Nominal and verbal morphologies of Motuna are highly complex and elaborate. All the nominals belong to a fully grammaticalised noun class system based on their natural genders (masculine/neuter, feminine, diminutive, local and manner), while some of them are optionally categorised by classifiers combined with numerals, demonstratives, verbs, etc. (Chaps 4 and 8). Among nominals, kinship terms constitute possessive constructions where pronominal possessors are obligatorily marked by pronominal prefixes. Some local nouns have deictic functions, indicating locations or directions. Pragmatic functions of NPs are indicated by word order, case markings and the demonstrative/article (Chaps 3, 6, and 10).

Verbs can be classified according to the cross-referencing markings they take. About half the verb stems of Motuna are ambi-transitive, taking both transitive (A and O) and middle (S) suffixes. The rest are mostly intransitive. Intransitive verbs are of four types: (1) Sa type taking A-type suffixes, (2) So verbs taking O-type suffixes, (3) middle type, and (4) five most frequently used irregular verbs. Causative and applicative valency-changing suffixes productively derive transitive verbs from these stems (Chaps 12-14). Motuna has an extensive tense/aspect/mood system (Chap 15). Clauses are mainly combined by medial verbs (sensitive to switch-reference and relative aspects) and relative clauses (Chap 17).