The antipassive voice is a verb voice found mostly in ergative languages. Like the passive voice, the antipassive decreases the verb's valency by one.

The antipassive works on transitive verbs by deleting the object (marked with the absolutive case) and changing the subject from ergative to absolutive.

"Mary-ERG eats pie-ABS." → "Mary-ABS eats."

"He-ERG is telling the truth-ABS." → "He-ABS is talking."

As with passive voice, the deleted argument can be re-introduced as an optional complement or oblique argument.

"Mary-ERG eats pie-ABS." → "Mary-ABS eats from the pie."