Nazi
Artical Nutshell: National Socialists never called themselves Nazis.
A rude word
1930, noun and adjective, from the German abbreviation of German pronunciation of Nationalsozialist (based on earlier German sozi, popular abbreviation of "socialist"), from Nationalsozialistische Deutsche Arbeiterpartei "National Socialist German Workers' Party,"
The NSDAP for a time attempted to adopt the Nazi designation as what the Germans call a "despite-word," but they gave this up, and the NSDAP generally avoided the term. Before 1930, party members had been called in English “National Socialists”, which dates from 1923. The use of Nazi Germany, Nazi regime, etc., was largely popularized as a derogatory epithet by German exiles abroad. From them, it spread into other languages, and eventually was brought back to Germany, only after the war. In the USSR, the terms national socialist and Nazi were said to have been forbidden after 1932, presumably to avoid any taint to the “good” word socialist. Soviet literature refers to the national socialists solely as fascists.
To many modern critical social justice activists, the word nazi has become a very broad derogatory slang word, like "nigger", except directed at any authoritative figure or person of European heritage that they may take issue with. The word Nazi is often used interchangeably to mean “authoritarian”, “racist”, “conservative” "hillbilly", or "ignorant person". This is common to the degree that it spurred popular memes to criticize the phenomenon.
The word Nazi was never used by National Socialists to describe themselves. It is offensive, and indicative of an individual largely unfamiliar with National Socialist theory and beliefs.