Hosting the German foreign minister this week, Prime Minister Benjamin Netanyahu used an especially tainted term to condemn the Palestinian demand that Israel's settlements in the occupied West Bank be removed.
"Judea and Samaria cannot be Judenrein," a Netanyahu confidant quoted him as telling Frank-Walter Steinmeier.
Asked how Germany's top diplomat responded to hearing the Nazi Holocaust term for areas "cleansed of Jews", the confidant said, "What could he do? He basically just nodded."
Protocol might have indicated that a representative of the country that carried out the World War II genocide, and which has since made much effort to atone, be spared such invocations.
Meanwhile, the confidant said Netanyahu had encouraged cabinet colleagues to deploy the term Judenrein in their defense of the settlements and of Israel's insistence that Palestinians recognize it as a Jewish state.
Briefing foreign reporters last week, Deputy Prime Minister Dan Meridor, a stalwart of Netanyahu's Likud party, urged them to ask whether "Palestinians would accept that Jews will live among them, or whether it is going to be totally not allowed."
"'Judenrein' is the term that was once used in other countries," Meridor said darkly, in remarks echoed the next day by another Likud minister who briefed journalists and diplomats.
Some diplomats have quietly questioned the propriety of applying such comparisons to a Middle East conflict which is a unique mix of race and religion, conquest and coexistence.
German officials made no comment on the terminology.