The term "Nazi" derives from the name given in German to a party member Nationalsozialist (German pronunciation: [natsi̯oˈnaːlzotsi̯aˌlɪst]) and was coined in response to the German term Sozi (pronounced [ˈzoːtsiː]), an abbreviation of Sozialdemokrat (member of the Social Democratic Party of Germany). Members of the party referred to themselves as Nationalsozialisten (National Socialists), rarely as Nazis. The term Parteigenosse (party member) was commonly used among Nazis, with the feminine form Parteigenossin used when it was appropriate.
The term was in use before the rise of the party as a colloquial and derogatory word for a backward peasant, characterising an awkward and clumsy person. It derived from Ignaz, being a shortened version of Ignatius, a common name in Bavaria, the area from which the Nazis emerged. Opponents seized on this and shortened the party's name in intentional association to the long-time existing Sozi to the dismissive "Nazi".
In 1933, when Adolf Hitler assumed power of the German government, usage of the designation "Nazi" diminished in Germany, although Austrian anti-Nazis continued to use the term derogatorily. The use of "Nazi Germany" and "Nazi regime" was popularised by anti-Nazis and German exiles abroad. Thereafter, the term spread into other languages and eventually was brought back to Germany after World War II. In English, the term is not considered a slang word, and has such derivatives as Naziism and denazification.