Tariana has three open lexical classes, two semi-closed classes and twelve closed classes of words.

Open word classes

Three open word classes are verbs, nouns and adjectives. The word classes differ in their grammatical categories, in the word class-changing derivational processes they participate in, and in the functional slots in the clause which they typically occupy. Verbs are prototypical predicates, while nouns are prototypical heads of noun phrases, and adjectives are prototypical modifiers. Subclasses of verbs, nouns and adjectives are discussed in §§3.1.1-3. An overview of word class-changing morphological devices is given in §3.1.4.

Verbs

VERBS can be cross-referenced for person, number and gender; their valency can be changed with valency-reducing or valency-increasing derivations (causative, passive, reciprocal), they take a negative suffix, and verbal classifiers (see §5.1.5 and Chapters 12-13, 17). They often host tense-aspect-evidentiality, mood and Aktionsart clausal enclitics (see Chapters 14-16). They can form serial verb constructions and complex predicates (see Chapters 18-19).

Verbs divide into two classes: those which take prefixes (cross-referencing, relativising and negative) and those which do not. Active transitive and intransitive verbs obligatorily take cross-referencing prefixes to mark the A/Sa constituent (see Preface). Stative (So) verbs and verbs of physical states (Sio) do not take any cross-referencing markers. This division roughly corresponds to the morphological distinction between active and stative intransitive verbs inherited from Proto-Arawak (see Aikhenvald 1999b).