What were the terms given by the Nazis when they wanted to convey the words 'kill' or 'murder in their official communications ?

The Nazis used the words 'special treatment or final solution' to convey mass killing of the Jews. The words , 'selection or disinfection' was used for the elimination of the disabled and to deport people to the Gas Chambers the Nazis used the word 'evacuation'. Gas Chambers were called 'disinfection areas'. These chambers looked like a bath rooms with fake showerheads.