任职 means 'to assume office' or 'to serve in a post'. It combines 任 (rèn), meaning 'to appoint' or 'to take on responsibility', and 职 (zhí), meaning 'duty', 'post', or 'position'. Together, they form a formal verb indicating the act of officially beginning to hold a job, especially in government, education, or corporate leadership roles. It emphasizes the formal start of service in a designated capacity, not just employment in general.

This term is commonly used in official announcements, news reports, and professional biographies — for example, when reporting that someone has become mayor, university president, or board director. It is rarely used for everyday jobs like cashier or driver; those contexts use words like 工作 or 就职 instead. The verb often appears with time markers (e.g., 自2023年起任职) or in passive constructions (e.g., 被任命为...并任职).