(grammar) The vocative case

(grammar) A word in the vocative case

(rare) Something said to (or as though to) a particular person or thing; an entreaty, an invocation.

Of or pertaining to calling; used in calling or vocation.

(grammar) Used in address; appellative (said of that case or form of the noun, pronoun, or adjective, in which a person or thing is addressed). For example "Domine, O Lord"