grammar - What are words like "Hey Man", "Hey you", "Hey Dude" called

Is there a term for words that summon someone like "Man," "Dude," "Kid" in sentences such as "Hey, Dude," "Listen up, kid," etc?

I am sure there is, but I can't really remember what it is.

Answer

I think you might be thinking of vocative.

of a word or word group: marking the one addressed (as mother in “mother, come here”)