Sonderbehandlung is any sort of preferential treatment. However, the word Sonderbehandlung was used as a euphemism for mass murder by Nazi functionaries and the SS, who commonly used the abbreviation S.B. in documentation. It first came to prominence during Aktion T4, where SS doctors killed mentally ill and disabled patients between 1939 and 1941, and was one of a number of nonspecific words the Nazis used to document mass murder and genocide. Another notable example was Sonderbehandlung 14f13.

A euphemism is an innocuous word or expression used in place of one that is deemed offensive or suggests something unpleasant. Some euphemisms are intended to amuse, while others use bland, inoffensive terms for concepts that the user wishes to downplay. Euphemisms may be used to mask profanity or refer to topics some consider taboo such as mental or physical disability, sexual intercourse, bodily excretions, pain, violence, illness, or death in a polite way.