The vocative case (abbreviated ) is the case used for a noun identifying the person (animal, object, etc.) being addressed and/or occasionally the determiners of that noun. A vocative expression is an expression of direct address, wherein the identity of the party being spoken to is set forth expressly within a sentence. For example, in the sentence, "I don't know, John," John is a vocative expression indicating the party who is being addressed, as opposed to the sentence "I don't know John," where John is the direct object of the verb, "know."
Historically, the vocative case was an eleme...