For a close friend:
* Kumpel: This is the most common and versatile word, similar to "buddy" or "pal."
* Freund: This means "friend" and works for closer friendships, but can sound too formal in some contexts.
* Bruder: This means "brother" and is used for very close friends, almost like family.
For someone you're addressing informally:
* Mann: This literally means "man" but is used like "mate" in casual settings, especially among men.
* Alter: This literally means "old one" and is a playful and informal way to address someone.
In specific contexts:
* Partner: This can be used in business or professional settings, similar to "business partner" or "colleague."
* Kollege: This means "colleague" and is used in professional settings.
It's best to use the word that fits the situation and your relationship with the person.
For example:
* "Hey Kumpel, what's up?" (Hey mate, what's up?)
* "Ich bin mit meinem Partner im Geschäft." (I'm in business with my partner.)
* "Komm schon, Alter, lass uns eine Runde spielen!" (Come on, mate, let's play a round!)
It's always a good idea to consider the context and formality level when choosing a word.