egregious - bad
‘Egregious’ is a formal word used to express something that stands out due to how bad or shocking it is. It tends to be used more in a professional context, particularly in the form of an official reprimand or a newspaper report.
You have made a number of errors, but your latest was the most egregious.
The dictator oversaw some of the most egregious abuses of human rights ever recorded.
The ruler of that country seems to have little regard for either international law or his citizens who he so egregiously exploits.