Bahasa Istana (Palace Language) or Bahasa Dalam (Internal Language) is a Malay sociolect used among the Brunei and Malaysian royal families either for internal communication or when announcing the affairs of the king or sultan.

In Brunei 
In the context of Brunei Malay, Bahasa Dalam is better known as Bahasa Raja-Raja or Bahasa Orang Istana. 

Bahasa Dalam is not only used by the royal family, but also by people in the upper class who hold titles, important roles in society, or certain positions in the government. Most of those who are proficient in using Bahasa Dalam come from Kampong Ayer and live along the Brunei River.

Bahasa Dalam sometimes utilizes a different vocabulary from the commonly used Brunei Malay. At other times, it uses the more common vocabulary, but is spoken with a lowered tone and intonation, soft, polite and arranged in a figurative context.

In Malaysia 
Bahasa Istana is a dialect rich in courtesy and politeness. It is used for communication between the royal family and the common people or when talking about the affairs of the ruler and the palace, especially in an official context.

Vocabulary 
The vocabulary of Bahasa Istana is as follows:

References 

Languages of Brunei
Languages of Malaysia
Malay dialects