obdurate

The obdurate employee kept arriving late despite several written warnings.

这个顽固不化的员工屡次迟到，尽管收到过好几份书面警告。

Her father was obdurate and refused to speak to her after the argument.

她父亲铁石心肠，争吵之后拒绝和她说话。

The landlord remained obdurate to the tenants' pleas for a lower rent.

房东对租户们降低租金的请求仍然无动于衷。