inexcusable

I fear lest we commit an inexcusable blunder.

It is inexcusable to be late for an important meeting.

Stealing is an inexcusable behavior.

Violence against others is always inexcusable.

It is inexcusable to ignore someone in need of help.

Lying to cover up your mistakes is inexcusable.

Cheating in exams is considered inexcusable in most schools.

Not taking responsibility for your actions is inexcusable.

Discrimination based on race is inexcusable.

Ignoring safety regulations is inexcusable in a workplace.

Bullying others is an inexcusable behavior.