unmöglich zu erwähnen

listen to the pronunciation of unmöglich zu erwähnen
Deutsch - Englisch
unmentionable
{i} something that cannot be said, something that cannot be mentioned
Not mentionable
unsuitable or forbidden as a topic of conversation; "unmentionable words
unsuitable or forbidden as a topic of conversation; "unmentionable words"
If you describe something as unmentionable, you mean that it is too embarrassing or unpleasant to talk about. Has he got some unmentionable disease?. too shocking or embarrassing to talk about