Chapter 116The Desiderative rusuy

116.1 The auxiliary and its form

The postverbal auxiliary rusuy ‘want to’ follows the lexical verb directly, with no intervening conjunction. This places it in the auxiliary (A) frame that the TAM overview distinguishes from the pair-verb frame on the basis of person marking: in V rusuy, only the lexical verb V carries person agreement; rusuy is morphologically invariant regardless of the number or person of the experiencer Nakagawa (2024: 306, 312–313); Bugaeva (2012: 493).

Nakagawa groups rusuy in 表74 alongside a, aan, nankor, easirki, and several further items as 本来的な助動詞 (proper auxiliaries of the Saru dialect). The defining property of all members of that table is the absence of an independent verbal use — with one exception: rusuy alone retains a use as a full verb alongside its auxiliary function Nakagawa (2024: 306). That exceptional status is discussed in the section below. Bugaeva classifies rusuy as a desiderative modal without further qualification Bugaeva (2012: 493). Tamura's 1960 study of Saru auxiliaries describes the form in its original Japanese-language analytical context Tamura (1960).

The construction appears in Saru narrative, conversational, and formal texts alike, and the accessible sources document no restriction to a particular speech level.

116.2 Fusion and lexicalization

rusuy exhibits a strong tendency to fuse phonologically with the preceding verb stem, producing single lexicalized units. Two forms are explicitly documented for Saru: arparusuy 'want to go' (from arpa ‘go (SG)’ + rusuy) and iperusuy 'want to eat a meal' (from ipe ‘eat a meal’ + rusuy) Nakagawa (2024: 312–313). The morphological closeness parallels the lexical incorporation of an action-verb root into the abilitative easkay, which yields fused forms such as sinotca-easkay 'be able to compose songs' Nakagawa (2024: 315). Both auxiliaries therefore sit at an intermediate point on the continuum from syntactic auxiliary to derivational suffix, and the desiderative fusions represent points closer to the lexicalized end of that cline ‹corpus-suggested›.

116.3 Argument structure and the experiencer

The person who wants must be the same individual who would perform the action: in V rusuy, the experiencer of the desire and the would-be agent or subject of V are necessarily coreferential. No separate morphological device marks this relation; it follows from the single person-agreement slot on V. For a transitive lexical verb, agent and object agreement appear in the normal position on V:

Ainu has no infinitive: the language does not permit a non-finite verbal complement. Where many languages use a to-infinitive ('I want to go'), Ainu requires a finite auxiliary construction such as V rusuy or, in other complementation contexts, a nominalization with the formal nouns pe, hi, or kuni. This follows from the head-marking architecture of the verb, under which every finite predicate carries a person index. The desiderative construction handles one of the core functions that infinitival complements serve in other languages Ijäs (2023). Community discussion has made the same observation: nukopoli aynu-corpora Discord (2023–2026) (nukopoli, aynu-corpora Discord 2024-11-25) notes that ku=e rusuy, ku=e easkay, and the kuni nominalization divide the work that a single to-infinitive carries in English — a lead consistent with the typological profile of head-marking, nominalization-dependent languages (nukopoli, aynu-corpora Discord 2024; aynu-corpora Discord (2023–2026)) ‹speculative›.

116.4 Rusuy as full verb: the dual status

Nakagawa's explicit exception note — that rusuy is the only member of 表74 to retain an independent verbal use — implies a structural distinction between two modes of use Nakagawa (2024: 306):

The diagnostic between the two modes is position and the locus of person agreement. When rusuy follows a person-marked lexical verb and is itself bare, the auxiliary reading holds. When rusuy receives its own person prefix without a preceding person-marked verb, it functions as the clause's main predicate. The exact frequency and distribution of the full-verb use are not documented with corpus examples in the accessible sources; the distinction rests on Nakagawa's descriptive note ‹corpus-suggested›. The abilitative easkay offers a partial parallel in that it too appears both as an auxiliary following a person-marked verb and as a predicate in its own right; unlike rusuy, however, it belongs to 表75 (the transitive-verb auxiliary group) and is classified as a transitive verb throughout, making its dual status structurally different Nakagawa (2024: 314–315). The rusuy case is therefore the only instance in 表74 of a proper auxiliary with documented verbal currency.

116.5 Possession desire: kor rusuy

When the object of desire is a thing rather than an action, the standard strategy uses the transitive possessive verb kor ‘have, possess, hold’ as the lexical V. The possessed entity — the thing wanted — appears as the object of kor, and rusuy attaches in its normal auxiliary position: Bugaeva (2012: 467); Nakagawa (2024: 421)

kor rusuy is thus a sub-case of V rusuy in which V is the possessive verb kor 'have'. The semantic contrast it encodes — thing-desire versus action-desire — is crosslinguistically common in languages that use a single desiderative auxiliary: Nakagawa (2024)

116.6 The applicative-desiderative

The applicative prefix e- ‘applicative’ (treated fully in Chapter 79 (The e- Applicative)) introduces a new patient, goal, or stimulus argument to an otherwise intransitive verb. When that transitivized verb precedes rusuy, the result is an applicative-desiderative expressing desire directed toward an explicit referent: Bugaeva (2022); Bugaeva (2012: 469)

The construction is the regular intersection of the desiderative auxiliary frame with the applicative system. rusuy attaches in its normal postverbal position, person marking follows the same rule (on the lexical verb only), and the semantic contribution of e- is governed by the applicative semantics of Chapter 79 (The e- Applicative). The accessible sources do not provide corpus examples specifically for the e-V rusuy combination; the account here rests on the independently documented behaviour of both components ‹corpus-suggested›. Where the lexical verb is already transitive — as in ku=e rusuy 'I want to eat it' — the applicative prefix is not needed, and the object agreement appears on the transitive stem in the normal way.

116.7 Negation and scope

Negation of the desiderative complex places somo before the lexical verb and its person agreement, bringing the whole V rusuy predicate into the scope of negation:

The placement parallels the general negation pattern for the auxiliary frame: negation in Ainu is clause-internal and sits inside any outer evidential projection Nakagawa (2024: 393). Within the desiderative predicate itself, the nesting order follows the auxiliary stacking constraint: aspect auxiliaries attach to the lexical verb, and rusuy scopes over the resulting aspectual complex. An evidential frame such as ruwe ne then closes the whole expression — the ordering V rusuy ruwe ne 'it is a recognized fact that one wants to V' is expected and the reverse *ruwe ne V rusuy would be ill-formed, in line with the general constraint that the evidential takes widest scope among the clause-internal operators Nakagawa (2024: 393). The full modal field in which rusuy sits — alongside the epistemic nankor and the prospective kusu ne — is treated in Chapter 119 (Epistemic Modality, Dubitative, Intentive, and Irrealis), and the deontic space adjacent to the desiderative in Chapter 118 (Deontic Necessity and Obligation (kuni ne, kus ne)).

116.8 Semantic range: community observations

The core value of rusuy is desiderative: it predicates a desire on the part of the grammatical subject to perform the action of the preceding verb. In practice, and particularly with verbs of bodily state or emotional reaction, the meaning can shade into an imminent-event reading. The community member nukopoli has proposed a comparison with Chinese 要 (yào), which covers both 'want to' and 'be about to', citing mokor rusuy 'want to sleep / be getting sleepy' and cis rusuy 'want to cry / be about to cry' as illustrative cases aynu-corpora Discord (2023–2026) (nukopoli, aynu-corpora Discord 2024-11-29). The same observation raises a possible morphological link between rusuy and rawe, but no independent phonological or semantic evidence supports this etymology in the accessible sources ‹speculative›. The near-future shading is best understood as a pragmatic inference from the desiderative meaning rather than a separate grammaticalized prospective value; the grammaticalized prospective function in Ainu is carried by kusu ne and related forms, treated in Chapter 119 (Epistemic Modality, Dubitative, Intentive, and Irrealis).