vocative
/ˈvɒkətɪv/Definitions
1. noun
A word or phrase used to address someone or something, typically at the beginning of a sentence.
“The vocative in the letter was ‘My dearest wife’.”
2. adjective
Used to describe words or phrases that are used to address someone or something.
“The vocative form of ‘hello’ is different from its nominative form.”