What does each letter in the word Nazi stand for?

Answer:

The word isn't actually an acronym but is based on syllables, so it's not a matter of each letter standing for something. (The recent habit of spelling the word all in capitals is misleading and very ignorant).

The word Nazi is based on the first two syllables of the German word Nationalialsozialist. (In German 'ti' as in 'National' is pronounced /tsi/).

The term 'Nazi' was in widespread use in Germany as a mildly derogatory term in the early 1930s. It was inspired by the use of 'Sozi' for socialists. (Compare with 'Commie' for 'Communist'). Rival gangs of young kids in German school playgrounds in the early 1930s called themselves 'Nazis' or 'Sozis' and fought one another.

Note:

  1. In German the word is a noun only, and cannot be used as an adjective.
  2. In some dialects in southern Bavaria the word predates the rise of any National Socialist party or ideology, and means a (comically) clumsy man, buffoon.
  3. Again in some parts of southern Bavaria, Nazi had been in use for a long time as a nickname for Ignaz.

Nationalsozialistische Deutsche Arbeiterpartei, or National Socialist German Workers' Party in English.