Unaccusative Verb

In linguistics, an unaccusative verb is an intransitive verb whose (syntactic) argument is not a (semantic) agent; that is, it does not actively initiate, or is not actively responsible for, the action of the verb; or that treats the argument like the accusative argument of a transitive verb. Unaccusative verbs thus contrast with unergative verbs. An unaccusative verb's subject is semantically similar to the direct object of a transitive verb, or to the subject of a verb in the passive voice. English unaccusative verbs include die and fall, but not run or resign, which are unergative. They are called unaccusative because, although the subject has the semantic role of a patient, it is not assigned accusative case.

In nominative–accusative languages, the accusative case, which marks the direct object of transitive verbs, usually represents the non-volitional argument (often the patient). But for unaccusative verbs, the subject is non-volitional and yet is not marked by the accusative.