擅自 (shàn zì): โดยไม่มีการอนุญาต

The company's financial data is confidential; without approval, no one may access it without authorization.

In a fit of anger, he left his post without permission and was severely criticized by his boss.

Hospital rules state that patients must not adjust the IV drip rate on their own; a nurse must do it.

Parents reading their child's diary without permission can make the child feel their privacy is violated, thus damaging parent-child trust.