Labile verb

In general linguistics, a labile verb (or ergative / diffused / ambivalent verb) is a verb that undergoes causative alternation; that is, it can be used both transitively and intransitively, with the requirement that the direct object of its transitive use corresponds to the subject of its intransitive use, as in "I ring the bell" and "The bell rings." Labile verbs are a prominent feature of English, and also occur in many other languages. This behavior can be seen as evidence that the distribution of verb classes in that language does not depend on transitivity. In this respect, it is a phenomenon that is common to both Active languages and Ergative languages. This is because they are often not possible to distinguish between transitive and intransitive verbs in terms of word formation or morphology. They have the same morphological form or suffix regardless of whether they are transitive or intransitive, and the transitivity or intransitivity of the verb is determined by the context.

When causatively alternating verbs are used transitively they are called causatives since, in the transitive use of the verb, the subject is causing the action denoted by the intransitive version. When causatively alternating verbs are used intransitively, they are referred to as anticausatives or inchoatives because the intransitive variant describes a situation in which the theme participant (in this case "the bell") undergoes a change of state, becoming, for example, "rung".