gross misconduct

Translations
грубое нарушение
The employee was fired for gross misconduct.
Сотрудник был уволен за грубое нарушение.
Definitions
Gross misconduct refers to behavior by an employee that is so serious it justifies immediate dismissal from their job, without the need for prior warnings or disciplinary procedures. This can include actions such as theft, violence, fraud, or serious breaches of company policy.
Words
gross

adjective
грубый
misconduct

noun
проступок