From Hannah Arendt’s “Eichmann in Jerusalem” (chapter 6):
Furthermore, all correspondence referring to the matter was, subject to rigid “language rules,” and, except in the reports from the Einsatzgruppen, it is rare to find documents in which such bald words as “extermination,” “liquidation,” or “killing” occur. The prescribed code names for killing were “final solution,” “evacuation” (Aussiedlung), and “special treatment” (Sonderbehandlung); deportation - unless it involved Jews directed to Theresienstadt, the “old people’s ghetto” for privileged Jews, in which case it was called “change of residence” - received the names of “resettlement” (Umsiedlung) and “labor in the East” (Arbeitseinsatz im Osten), the point of these latter names being that Jews were indeed often temporarily resettled in ghettos and that a certain percentage of them were temporarily used for labor.
Only among themselves could the “bearers of secrets” talk in uncoded language, and it is very unlikely that they did so in the ordinary pursuit of their murderous duties - certainly not in the presence of their stenographers and other office personnel. For whatever other reasons the language rules may have been devised, they proved of enormous help in the maintenance of order and sanity in the various widely diversified services whose cooperation was essential in this matter. Moreover, the very term “language rule” (Sprachregelung) was itself a code name; it meant what in ordinary language would be called a lie. For when a “bearer of secrets” was sent to meet someone from the outside world - as when Eichmann was sent to show the Theresienstadt ghetto to International Red Cross representatives from Switzerland - he received, together with his orders, his “language rule,” which in this instance consisted of a lie about a nonexistent typhus epidemic in the concentration camp of Bergen-Belsen, which the gentlemen also wished to visit. The net effect of this language system was not to keep these people ignorant of what they were doing, but to prevent them from equating it with their old, “normal” knowledge of murder and lies.
The subtitle of this well known book is “A Report on the Banality of Evil”, and what is most morally shocking is the normalcy with which Eichmann, his peers, and his superiors went about the business of rounding up and systematically murdering human beings. Every once in a while an acknowledgement of moral doubt peeks through, for example from Eichmann’s tales of warmly meeting Jewish leaders during the deportation stages of his career, but during his work it was never of any import.
He knew what he was working on, as did his colleagues, that it was murder, it was depraved killing, starvation, burning of families, but they couldn’t call it that. They needed jargon to obscure the true nature of what they were doing, not just from the international community - so they wouldn’t intervene? so they could convince themselves that nothing evil was afoot? - but from themselves, to make it easier to treat it like work and to suspend their own questions and conscience, in the event these ever appeared.