Vocative case
The vocative case is a grammatical case that is present in some languages. In general it is used for nouns, to address a specific person. In many modern languages it no longer exists, as this function is often taken by the nominative case.
Vocative Case Media
Sign at Aberystwyth University in Welsh displaying use of the vocative case – myfyrwyr 'students' mutated to fyfyrwyr
"Et tu, Brute?" from Shakespeare's Julius Caesar, probably the most famous use of the vocative in literature.
