inakzeptabel
unacceptable
Completely unacceptable; so bad or inappropriate that one cannot tolerate or accept it.
Eine solche Verzögerung bei der Lieferung ist für uns absolut inakzeptabel.
Such a delay in delivery is absolutely unacceptable for us.

unacceptable
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unacceptable
Completely unacceptable; so bad or inappropriate that one cannot tolerate or accept it.
Eine solche Verzögerung bei der Lieferung ist für uns absolut inakzeptabel.
Such a delay in delivery is absolutely unacceptable for us.

The word is made up of the prefix 'in-' and the adjective 'akzeptabel' (acceptable). The prefix 'in-' here means 'not', so something is 'inakzeptabel' (unacceptable) if it cannot be accepted.
Sein Verhalten auf der Feier war wirklich inakzeptabel.
His behavior at the party was really unacceptable.
To emphasize strong disapproval, 'inakzeptabel' (unacceptable) is often combined with adverbs such as 'völlig' (completely), 'absolut' (absolutely), or 'gänzlich' (entirely).
Wir halten diese Bedingungen für absolut inakzeptabel.
We consider these conditions absolutely unacceptable.
'Inakzeptabel' (unacceptable) is a strong word and is often used in formal or official contexts, for example in complaints, business negotiations, or political discussions.
Der Vorschlag wurde von der Kommission als inakzeptabel zurückgewiesen.
The proposal was rejected by the commission as unacceptable.
impossible
'unmöglich' and 'inakzeptabel' can both say that something is not okay and should not be tolerated. 'unmöglich' often sounds more personal and more colloquial, especially with bad behavior: 'Das war unmöglich.' (That was unacceptable.) 'inakzeptabel' sounds more objective and more like a clear boundary, for example with rules, work, school, or official situations. When you are reacting emotionally, 'unmöglich' is natural. When you want to say clearly and rather formally that something is not accepted, 'inakzeptabel' fits better.

Mein Kollege findet die langen Wartezeiten beim Arzt inakzeptabel.
My colleague finds the long waiting times at the doctor's office unacceptable.
Seine Bemerkung vor dem ganzen Team war wirklich unmöglich.
His comment in front of the whole team was really unacceptable.