Honorifics
In addition to the usual ranks and professional titles, it is customary to add Pak or Bapak and Saudara for addressing men, and Bu or Ibu for addressing women. Pak and Bapak are literally translated as "father", with Bapak being the more formal and used in speech much like the English word "sir." Saudara is a term of greater respect and formality, literally translated as "kinsman". Ibu is literally translated as "mother" and is used in speech much like the English words "ma'am" and "lady". If a person's name is unknown, it is possible to call an Indonesian man Bapak or an Indonesian woman Ibu. Another informal way in addressing significantly older people is to call them Om and Tante, which mean "uncle" and "aunt". The terms are Dutch-influenced and quite commonly used in big cities. However, local honorifics continue to be employed throughout Indonesia, such as the casual in general way Kakak is used for older sister/brother, in Javanese Mbak is used for older sister; Mas is used for older brother, in Sumatran Malay or Minangkabau cultural sphere is corresponds to Abang for older brother. Additionally, 'Gus' (from bagus), as used to address former president 'Gus Dur' is usually used exclusively to address honorable Eastern Javanese people with strong traditional and religious links.
Read more about this topic: Indonesian Names