Intransitive verb

In grammar, an intransitive verb does not take an object. In more technical terms, an intransitive verb has only one argument (its subject), and hence has a valency of one. For example, in English, the verbs "sleep", "complain" and "die", are intransitive.

Some examples of sentences with intransitive verbs:
* Harry will sleep until sunrise. (sleep has no object)
* You complain too much. (complain has no object)
* I die Friday. (die has no object)

Valency-changing operations

In languages where a passive voice exists, a transitive verb can be used in the passive voice in order to turn it into an intransitive one. For example, the transitive verb "hug" becomes the intransitive verb phrase "be hugged". The passive voice involves deleting the subject and replacing it by the direct object (this shift is called "promotion" of the object).

Intransitive verbs, of course, cannot be used in the passive voice in the strict sense, However, some languages (like Dutch) have so-called "impersonal passives" that allow one to transform, e. g. "He phoned"

Ambitransitivity

In many languages, there are ambitransitive verbs, which can be either transitive or intransitive. For example, English "play" is ambitransitive (both intransitive and transitive), since it is grammatical to say "His son plays", and it is also grammatical to say "His son plays guitar". English is rather flexible with regards to verb valency, and so it has a high number of ambitransitive verbs; other languages are more rigid and require explicit valency changing operations (voice, causative morphology, etc.) to transform a verb from intransitive to transitive or vice versa.

In some ambitransitive verbs, called "ergative verbs", the alignment of the syntactic arguments to the semantic roles is exchanged. An example of this is the verb "break" in English.

:(1) "I broke the cup.":(2) "The cup broke."

In (1), the verb is transitive, and the subject is the "agent" of the action, i. e. the performer of the action of breaking the cup. In (2), the verb is intransitive and the subject is the "patient" of the action, i. e. it is the thing affected by the action, not the one that performs it. In fact, the patient is the same in both sentences, and sentence (2) is an example of implicit middle voice. This has also been termed an "anticausative".

Other alternating intransitive verbs in English are "change" and "sink".

In the Romance languages, these verbs are often called "pseudo-reflexive", because they are signaled in the same way as reflexive verbs, using the clitic particle "se". Compare the following (in Spanish):

:(3a) "La taza se rompió." ("The cup broke."):(3b) "El barco se hundió." ("The boat sank."):(4a) "Ella se miró en el espejo." ("She looked at herself in the mirror."):(4b) "El gato se lava." ("The cat washes itself.")

Sentences (3a) and (3b) show Romance pseudo-reflexive phrases, corresponding to English alternating intransitives. As in "The cup broke", they are inherently without an agent; their deep structure does not and can not contain one. The action is not reflexive (as in (4a) and (4b)) because it is not performed by the subject; it just happens to it. Therefore, this is not the same as passive voice, where an intransitive verb phrase appears, but there is an implicit agent (which can be made explicit using a complement phrase):

:(5) "The cup was broken (by the child).":(6) "El barco fue hundido (por piratas)." ("The boat was sunk (by pirates).")

Other ambitransitive verbs (like "eat") are not of the alternating type; the subject is always the agent of the action, and the object is simply optional. A few verbs are of both types at once, like "read": compare "I read", "I read a magazine", and "this magazine reads easily".

Cognate objects

In many languages, including English, some or all intransitive verbs can take "cognate objects" — objects formed from the same roots as the verbs themselves; for example, the verb "sleep" is ordinarily intransitive, but one can say, "He slept a troubled sleep", meaning roughly "He slept, and his sleep was troubled."

ee also

*Transitivity (grammatical category)
* Transitive verbs
* Verbs
* Ditransitive verbs
* Valency (linguistics)
* Morphosyntactic alignment