Formal:
* Anna (അന്ന): This is the most common and respectful way to address an elder brother.
* Chetta (ചേട്ട): Another respectful term, often used by younger siblings.
Informal:
* Annayya (അന്നയ്യ): A more casual and affectionate way to address an elder brother, often used among close family members.
* Chettan (ചേട്ടൻ): Similar to "Chetta," but more informal and commonly used among friends.
* Achan (അച്ഛൻ): While technically meaning "father," this can be used playfully to address an older brother, especially by much younger siblings.
The best way to call your elder brother depends on your relationship with him and the situation. It's always a good idea to observe how others address him and follow their lead.