What is the Islamic method or Sunnah for addressing an older brother or older sister?

The Prophetic Sunnah does not contain specific wordings for addressing an elder brother or an elder sister. However, there are general manners that encompass this:

1. Respect for the elder, for "He who does not show mercy to our young ones and acknowledge the right of our elders is not one of us."

2. Lowering one's voice when calling out or conversing, as stated in Luqman's admonition: (And lower your voice; indeed, the most disagreeable of sounds is the voice of donkeys.)

3. Addressing the person by the names and titles most beloved to them. If the people of a country are accustomed to a specific title for elder brothers and sisters, then it should be adhered to.

4. Adhering to the customary manners and traditions in each country for respecting elders, as long as they do not contradict Islamic law.