Formal:
* भाऊ (Bhauu) - This is the most common and formal way to say "brother".
Informal:
* बाबा (Baba) - This is a more casual way to say "brother", often used between siblings or close friends.
* भाई (Bhai) - This is another informal way to say "brother", borrowed from Hindi.
* अण्णा (Anna) - This is a term used to address an elder brother.
* धोणी (Dhoni) - This is a term used to address a younger brother.
The best word to use will depend on your relationship with the person you are talking to and the level of formality you want to convey.