Formal:
* Anna (அண்ணா): This is the most common and respectful way to address an older brother.
* Thambi (தம்பி): This is used to address a younger brother.
Informal:
* Akka (அக்கா): This is used to address an older sister.
* Thangai (தங்கை): This is used to address a younger sister.
* Saami (சாமி): This is a very familiar and informal term for "brother" and is typically used between close friends or siblings.
Other options:
* Aana (ஆனா): A slightly more casual version of "Anna".
* Thampiye (தம்பியே): A slightly more affectionate version of "Thambi".
* Ellarum (எல்லாரும்): Meaning "everyone", this can be used to address multiple siblings.
* Idhu (இது): This is a slang term used for a brother, similar to how English speakers might use the word "bro."
Remember:
* The choice of word will depend on the age of your brother and your relationship with him.
* Using "Anna" or "Thambi" is always respectful, even if your brother is younger than you.
* If you are unsure, it is always best to ask someone who speaks Tamil fluently for guidance.