Vocative adj. Of or pertaining to calling; used in calling; specifically (Gram.), used in address; appellative; said of that case or form of the noun, pronoun, or adjective, in which a person or thing is addressed; as, Domine, O Lord.
... Aba Sabir." There are five vocative particles in Arabic; "Ya," common to the near and far; "Aya" (ho!) and "Haya" (holla!) addressed to the far, and "Ay" and "A" (A-'Abda-llahi, O Abdullah), to those near. All govern the accusative of a noun in construction in the literary language ... — Supplemental Nights, Volume 1 • Richard F. Burton
...
